UK 99 C5 Manual resto project

[C5Steve]

Thanks - Very helpful! I am not an expert, just an enthusiast having a mess around with an old car. I really appreciate the advice.

The videos are more of a log of my progress for entertainment purposes (my own entertainment mainly), they're not meant to instruct or teach anything so apologies if you find the pratting around irritating!

From what you are saying then it looks like the VATS relearn process was unsuccessful in which case I need to follow the same steps but not open any doors?

For the next video you'll just need to bring the instruments inside the car for the 10 minute wait to avoid opening the doors I guess

I enjoyed the latest video and am pleased you're getting somewhere, I also had a chuckle when you were jacking it up as I also had the same panic the first time I jacked mine as to where to do it! I just use a timber under the front or rear subframe now and lift the entire front/back in one go for ease.

 

[Llewelyn]

If you think about it, that VATS and security system are from the same controller
So you're trying to do the VATS relearn and at the same time you're opening and closing the doors during the process, which interferes with the relearn process
As I mentioned, GM made this relearn process strict so to make it harder if someone is trying to steal the car by doing this process

Again when the door is opened that is what signals that controller and commands the light on dash to flash, if all is well
and hard on if something with VATS is wrong

There is a security seed code, both the PCM and BCM have to have sync'd that code up and agree they are the same, if not then it is commanded no fuel system functional to prevent starting and stealing the car

As mentioned also you do not want to wake up all other controllers to be yacking on the Starbus network so MUST not have anything else turned on like radio, lights, doors, etc

How this works

Programming Theft Deterrent System Components

Important:

• The body control module (BCM) must be programmed with the proper RPO configurations before performing learn procedures.
Refer to Body Control Module (BCM) Programming/RPO Configuration .

• If replacing the BCM with a GM Service Parts Operations (SPO) replacement part, the module will learn the passkey data code immediately. The existing PCM however, must learn the new fuel continue password when the BCM is replaced.

• If replacing a PCM with a GM Service Parts Operations (SPO) replacement part, after programming,
these modules will learn the incoming fuel continue password immediately upon receipt of a password message.

Once a password security seed message is received, and a password is learned, a learn procedure must be performed to change this password again. A PCM which has been previously installed in another vehicle will have learned the other vehicle's fuel continue password and will require a learn procedure after programming to learn the current vehicle's password.

Conditions
Use these procedures after replacing either controllers :

• BCM
• PCM

10 Minute Learn Procedure with Tech 2 or without further below)
Tools Required
• Tech 2
• Techline terminal with current SPS (Service Programming System) software

Connect the Tech 2 to the vehicle.
Select "Request Information" under "Service Programming".
Disconnect the Tech 2 from the vehicle and connect it to a Techline terminal.
On the Techline terminal, select "Theft Module Re-Learn" under "Service Programming".
Disconnect the Tech 2 from the Techline terminal and connect it to the vehicle.
Turn ON the ignition, with the engine OFF.
Select "VTD Re-Learn" under "Service Programming".
Attempt to start the engine, then release the key to ON (vehicle will not start).
Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF (the vehicle is now ready to relearn the password on the next ignition switch transition from OFF to CRANK).
Turn OFF the ignition, and wait 5 seconds.
Start the engine (the vehicle has now learned the password).
With the Tech 2 (scan tool), clear any DTCs.

30 Minute Learn Procedure ( can be done without the Tech-II)
I use a stop watch as times have to be exact and stay in the car, doors closed

1. Turn ON the ignition, with the engine OFF, doors closed and all other electronics off
2. Attempt to start the engine, then release the key to ON (vehicle will not start).
3. Observe the SECURITY telltale, after approximately 10 minutes the telltale will turn OFF.
4. Turn OFF the ignition, and wait 5 seconds.

5. Repeat steps 1 through 4 two more times for a total of 3 cycles/30 minutes
(the vehicle is now ready to relearn the password on the next ignition switch transition from OFF to CRANK).

Important:

The vehicle learns the password on the next ignition switch transition from OFF to CRANK.
You must turn the ignition OFF before attempting to start the vehicle.

Start the engine (the vehicle has now learned the password).
With a scan tool, clear any DTCs

If after doing this and open door, if the security light is NOT flashing than the process was not completed
and PCM will not command the fuel system to prevent stealing the car

Amazing info - And I really appreciate you sharing it with me. I'm not with the car (frustratingly!) so I'll check tomorrow and see if it cures the issue. Is actual cranking necessary or is keying on but without cranking sufficient? I am reading conflicting information online but if I am correct in thinking Passkey II requires cranking and Passkey III doesn't?

 

[Llewelyn]

For the next video you'll just need to bring the instruments inside the car for the 10 minute wait to avoid opening the doors I guess

I enjoyed the latest video and am pleased you're getting somewhere, I also had a chuckle when you were jacking it up as I also had the same panic the first time I jacked mine as to where to do it! I just use a timber under the front or rear subframe now and lift the entire front/back in one go for ease.

Haha! I bet we'd get a couple of guitars in there, not sure about the piano and drums though! I need a better jack really - Preferably a long reach very low one. SGS do some decent ones, I might treat myself at some point.

 

[teamzr1]

Amazing info - And I really appreciate you sharing it with me. I'm not with the car (frustratingly!) so I'll check tomorrow and see if it cures the issue. Is actual cranking necessary or is keying on but without cranking sufficient? I am reading conflicting information online but if I am correct in thinking Passkey II requires cranking and Passkey III doesn't?

To determine if the BCM and PCM are syn'c with the same security code, simply opening the drivers door the light flashes if OK
if hard on then a problem exists which in almost all cases is the relearn is needed
You cannot change the PCM as you did and expect it to have stored the exact same security code as the BCM in your C5 has, which was passed on and sync'd with the PCM you took out
Your own test by bypassing the fuel relay and engine starting shows the PCM is not commanding that relay as a security measure

Also, as I posted, there is a good chance the PCM does not have the same crank position sensor code and
thus once driving the C5, if there are misfires are going on than you also have to do a PCM to CPS relearn process
so that PCM knows position of cylinders to that sensor and the CAM sensor

 

[Llewelyn]

To determine if the BCM and PCM are syn'c with the same security code, simply opening the drivers door the light flashes if OK
if hard on then a problem exists which in almost all cases is the relearn is needed
You cannot change the PCM as you did and expect it to have stored the exact same security code as the BCM in your C5 has, which was passed on and sync'd with the PCM you took out
Your own test by bypassing the fuel relay and engine starting shows the PCM is not commanding that relay as a security measure

Also, as I posted, there is a good chance the PCM does not have the same crank position sensor code and
thus once driving the C5, if there are misfires are going on than you also have to do a PCM to CPS relearn process
so that PCM knows position of cylinders to that sensor and the CAM sensor

Thanks - From memory after I "completed" the relearn process ("completed" most likely meaning "failed"!) I pulled the codes and I believe I got

P1630
P1631
B2723

Reading up on this suggests as you say that the relearn process isn't complete... I've been a bit distracted recently by a very poorly family dog (this was something I was also worrying about during that last video so my concentration levels weren't great). Hoping to revisit the car soon with a clearer head and I will try everything you suggest and report back

Re the CPS relearning, I have a friend with Tech II so I should be able to get that sorted. Again, mixed info on the net - Some say the code doesn't cause any issues and others say it causes hesitation, misfiring etc. Either way I will get the code cleared.

 

[teamzr1]

As you see when I look inside the GM calibration for your C5 you notice both PCM DTCs arew for VATS


The B2723 DTC is coming from the BCM and may have another VATs issue as that says the ign key pellet is not connecting with the contacts
of the ign switch contacts for VATS

Else you guys are moving the key around when attempting to start the engine and causing the problem
In any case, first determine that the security light is flashing or not with just door opened

What you are seeing is the resistor LOSES CONTACT after the engine is started.

SOLUTION:

1- CLEAN the resistor contacts on the key with a pencil eraser and some alcohol and see if that resolves the issue.
Try using your SECOND key and see if that resolves the issue. If the resistor in your primary key is well-worn, it can lose contact.

2- Do you have a MASSIVE set of keys on your key ring that puts a lot of weight on the key when it’s in the ignition?? If so, remove the extra weight!

3- Sometimes the VATS Sensor on the end of the ignition switch just wears out and doesn’t work properly anymore.
To replace it, you have to order an entire replacement key cylinder and have the new cylinder re-pined to work with your OEM key at the lock smith or dealer.

You can open it up and clean /repair the little contacts.

 

[Llewelyn]

As you see when I look inside the GM calibration for your C5 you notice both PCM DTCs arew for VATS
View attachment 20930

The B2723 DTC is coming from the BCM and may have another VATs issue as that says the ign key pellet is not connecting with the contacts
of the ign switch contacts for VATS

Else you guys are moving the key around when attempting to start the engine and causing the problem
In any case, first determine that the security light is flashing or not with just door opened

What you are seeing is the resistor LOSES CONTACT after the engine is started.

SOLUTION:

1- CLEAN the resistor contacts on the key with a pencil eraser and some alcohol and see if that resolves the issue.
Try using your SECOND key and see if that resolves the issue. If the resistor in your primary key is well-worn, it can lose contact.

2- Do you have a MASSIVE set of keys on your key ring that puts a lot of weight on the key when it’s in the ignition?? If so, remove the extra weight!

3- Sometimes the VATS Sensor on the end of the ignition switch just wears out and doesn’t work properly anymore.
To replace it, you have to order an entire replacement key cylinder and have the new cylinder re-pined to work with your OEM key at the lock smith or dealer.

You can open it up and clean /repair the little contacts.

Thanks - Makes sense! I did check both keys (shown in video 2 I think) when I changed the ign barrel. I unplugged the resistor circuit connector and tested the resistance at that plug with the key (both keys) in the ignition. Might not have shown it on the video but I gave then a good jiggle around and the meter readings seemed rock solid stable so I think the contacts on the key, in the barrel etc are good. It is something I can check again though if needs be.

Working from memory so I'm not 100% sure but I may have succesfully cleared that B2723 code already come to think of it.

I'll be trying the VATS relearn procedure again tonight so I'll let you know how it goes

 

[teamzr1]

Cannot move forward until you can answer if the security light as of now when door opened is flashing or not

The PCM is marked for the 2 80 pin connectors red and blue

The wiring for the red connector, pin 9 as I show below is the command from PCM to control fuel pump relay
Would be simple with an OBD-II scanner or a Tech-II, to see when trying to start if PCM is commanding that relay or not
Check in fact pin 9 is DK GRN/WHT to assure you did not mismatch the colored end caps you took off and back on to the correct wiring connector
IF the security light is flashing, and you do not think the ign switch or its wiring is an issue, then you need to check that wire on
pin 9 to see if PCM is switching that circuit on and off, and if commanding on, then now check on the fuel relay does it also change there
to assure that wire for pin 9 is broke

RED connector wiring pins

Pin	Wire Color	Function
1	BLK/WHT	PCM Ground (Automatic Transmission Only)
2	BRN	TCC Control Solenoid (Automatic Transmission Only)
3	--	Not Used
4	PPL	AIR Solenoid Control
5	TAN/BLK	Torque Delivered
6	RED/BLK	Transmission Fluid Pressure Control Solenoid High (Automatic Transmission Only)
7	--	Not Used
8	LT BLU/WHT	Transmission Fluid Pressure Control Solenoid Low (Automatic Transmission Only)
9	DK GRN/WHT	Fuel Pump Relay Control
10	WHT	Engine Speed (Tach) Output Signal
11 - 13	--	Not Used
14	RED/BLK	A/C Refrigerant Pressure Sensor Signal
15	RED	Alternator L Terminal
16	--	Not Used
17	DK GRN/WHT	A/C Request Signal (C60 only)
18	DK GRN	A/C Status Signal
19	--	Not Used
20	PPL	Vehicle Speed Sensor (VSS) Reference Low
21	YEL	Vehicle Speed Sensor (VSS) Signal
22-24	--	Not Used
25	TAN	IAT Sensor Signal
26	PPL	Ignition Control 1
27	RED	Ignition Control 7
28	LT BLU/WHT	Ignition Control 6
29	DK GRN/WHT	Ignition Control 4
30	--	Not Used
31	YEL	MAF Sensor Signal
32	LT GRN	MAP Sensor Signal
33	DK BLU	Engine Cooling Fan Relay 2 and 3 Control
34	DK GRN/WHT	EVAP Canister Purge Valve Control
35	--	Not Used
36	BRN	AIR Pump Relay Control
37-38	--	Not Used
39	RED	Camshaft Position Sensor B+ Supply
40	BLK/WHT	PCM Ground
41	--	Not Used
42	TAN/BLK	TCC Enable Circuit (Automatic Transmission Only)
43	DK GRN/WHT	A/C Clutch Relay Control
44	LT GRN	Reverse Inhibit Solenoid Control
45	WHT	EVAP Canister Vent Valve Control
46	BRN/WHT	Malfunction Indicator Lamp (MIL) Control
47	WHT or YEL/BLK	1 to 4 Up-shift Lamp Control or Transmission Shift Solenoid B
48	LT GRN	Transmission Shift Solenoid A
49	--	Not Used
50	DK GRN/WHT	Vehicle Speed Output Circuit
51	YEL/BLK	Transmission Temperature Sensor Signal
52	GRY	Alternator F Terminal
53	--	Not Used
54	DK BLU	Fuel Level Sensor Signal
55-56	--	Not Used
57	PPL	IAT Sensor Ground
58	TAN/WHT	Engine Oil Pressure Sensor Signal
59	--	Not Used
60	BRN	Ignition Control Reference Low Bank 1
61	BRN/WHT	Ignition Control Reference Low Bank 2
62	GRY	PRND C Input Signal (Automatic Transmission Only)
63	PNK	Transmission Range Signal A (Automatic Transmission Only)
64	DK GRN	Fuel Tank Pressure Sensor Signal
65	--	Not Used
66	PPL/WHT	Ignition Control 8
67	RED/WHT	Ignition Control 2
68	DK GRN	Ignition Control 5
69	LT BLU	Ignition Control 3
70-72	--	Not Used
73	LT BLU	Fuel Level Sensor Signal (Secondary)
74-80	--	Not Used

 

[Llewelyn]

Thanks Team! Plenty to go on - I will be sure to update you!

 

[Llewelyn]

@teamzr1

An update as promised after a brief look last night (I didn't have time to actually start testing with a meter and jacking the car up etc):

Security light flashes when door is opened. I figured I would attempt VATS re-teach anyway in case it was somehow partially completed or corrupted somehow.

I did pull and clear the codes prior to re-teach but forgot to make a note of them!! There was only2 or 3 though.

Carried out re-teach procedure with a stopwatch (Crank/on 10 mins, off 5 secs and repeat x3 times)
Still no fuel pump activation

Pulled codes after re-teach and I got the following - A lot of them seem to be comms errors on the serial data bus. I have the shop manuals (physical copies) and will do some reading up today...

TCS
U1016 H
U1301 H

BCM
U1016H
U1096 H
U1255 H

PCM
P1626 H
P0230 C

HVAC
B0446 H

AO-LDCM
U1064 H

IPC
U1255 H

Dash also lit up like a Christmas tree with error messages for shocks inop, reduced engine power, etc etc.

NOTE a lot of the above could be to do with low voltage because my tender tripped out so I have no life support for the battery and it was quite low by the time the VATS re-teach had been done!

To me (luddite) it is pointing towards a grounding issue or wiring fault somewhere, or possibly an issue with the BCM (unlikely).

At the weekend I will start to have a thorough look with my meter and will double-check every ground (eg I haven't cleaned the engine grounds yet)...

Any advice on the above would be appreciated!

 

[teamzr1]

So being the security light flashes says the PCM and BCM agree on the security seed so not a issue

Controllers cannot function when voltage at the controllers is less than 12.5 volts, so the reason controllers are yacking on the
Starbus network and would cause the comm U codes.

Not only does the battery have proper voltage level, if battery cannot handle the current load when cranking would also cause
problems. You may have to get battery charged up and then do a battery load test to assure no cell(s) are bad

If battery than is working well and no start as my last post you need to check that wire and its pins from the red PCM connector to
the fuel relay to see if not the issue
Also make sure in taking PCM connector off and on that none of the pins got pushed backwards, so no connection or pins are too dirty

What was the reason the PCM was swapped ?
Was there acid damage from a battery leaking down there as common issue for side posts C5 battery ?

Yes since PCM controls function by reference to ground than grounds must be good and clean
PCM as you see has several ground wires.
There is a main engine ground, it is on the back of the engine on the left side and that goes to frame

I would correct what is needed for battery and test the wire as mentioned from PCM to fuel relay when cranking
Car has ground splice packs where several ground wires goes into a metal can as I show they can get corroded inside as I show here

 

[Llewelyn]

Cheers - It does make me wonder if it's just something very basic i.e. a ground or dodgy connection somewhere along the line... ! Looking forward to cracking on and working on this now, I really hope to sort out the fault over the weekend.

 

[Llewelyn]

@teamzr1

A quick update - I spent a couple of hours tonight doing a bit of further investigation and I've verified the following:

Ground signal to relay pin 85 solid and stable
Continuity from PCM connector pin 9 to relay pin 86 solid and stable

Checked star connectors next to BCM
Checked and cleaned (they were okay anyway) both ground points in the LHS/RHS kick panels in the interior

Still no further with curing it.

When I got home I did some reading of the service manual and I'm wondering if I need to "re-teach" the BCM which appears to be a process similar to the PCM passkey programming but involves 11mins on (no cranking) 30 secs off x3. I;m thinking maybe it's confused somewhere along the line and this is preventing the BCM to send the info back over serial comms to the PCM to enable the fuel pump relay? Either that or there is possibly a serial data comms iffy connection somewhere? OR when the PCM connections got wet maybe they shorted out part of the BCM (?) and the BCM has partially failed?

Any pointers or ideas would be appreciated!

 

[teamzr1]

You have not answered,
Why you changed the PCM,
Why did you think it was bad ?
Kind of hard that this has gone on for a few weeks, so we forget how this all started, really need to stick with it and get it solved

Was the no start the reason for the PCM swap, even though back than it could have needed the PCM/BCM relearn
Thought of swapping that old one back in (making sure the male pins are clean ) and see how that does ?

Is that a 5 pin relay, as I show here ?

If so with relay out, using multi meter
Using black probe to socket #86 to positive to 85, 12 volts
from 86 and 30 getting 12 volts
with key on, engine off 86 and 87, now getting 12 volts
As 87 takes that 12 volts to starter, have you checked from 87 to starter, solenoid is OK
and sure solenoid is OK ?

So still stands in question when cranking does pin 87 switches to 12 volts and when key off no voltage to 87 ?

IF via DIC or a OBD-II scanner, or a TECH-II report DTCs than the BCM is acting as the Starbus network and if showing any
P DTCs than it also is talking to PCM hence BCM is not the issue

 

[Llewelyn]

You have not answered,
Why you changed the PCM,
Why did you think it was bad ?
Kind of hard that this has gone on for a few weeks, so we forget how this all started, really need to stick with it and get it solved

Was the no start the reason for the PCM swap, even though back than it could have needed the PCM/BCM relearn
Thought of swapping that old one back in (making sure the male pins are clean ) and see how that does ?

Is that a 5 pin relay, as I show here ?

If so with relay out, using multi meter
Using black probe to socket #86 to positive to 85, 12 volts
from 86 and 30 getting 12 volts
with key on, engine off 86 and 87, now getting 12 volts
As 87 takes that 12 volts to starter, have you checked from 87 to starter, solenoid is OK
and sure solenoid is OK ?

So still stands in question when cranking does pin 87 switches to 12 volts and when key off no voltage to 87 ?

IF via DIC or a OBD-II scanner, or a TECH-II report DTCs than the BCM is acting as the Starbus network and if showing any
P DTCs than it also is talking to PCM hence BCM is not the issue
View attachment 21064

Thanks!

sorry I thought you knew - The PCM was full of water and there were clearly blown components on it. It’s toast I believe.

fuel pump relay is the standard 4 pin relay. I might have got the pin numbers wrong but essentially on the switch side of the relay where I expect to see continuity from pcm #9 output it’s all working correctly and the ground to the opposite side of that contact is perfect with good continuity.

When ignition is on there is no voltage on the switches side of the relay (85 in your drawing). The load side of the relay works fine when bridged so the fuel pump works.
Essentially the relay side of things is fine…

 

[teamzr1]

Well that changes everything, no I do not recall you posting the PCM a foot or higher from the ground was underwater
as that now says so was all the wiring, connectors, pins, Starbus, BCM and that fuse panel could also been in water
Sure now BCM could be bad
You need to start by checking the IGN fuses I show below and check the maxi fuses for starter and IGN in that fuse panel by PCM, and the female connectors fuses plug into

Then as I show in wiring there is a theft relay and another relay part of BCM




LOOK Closely at this starter wiring, both ign, starter and breaker fuses at fuse panel positions
47, 50, 52

 

[Llewelyn]

Thanks @teamzr1

The theft relay must be okay because the car cranks healthily. Also I have spark - I can start the car by bridging the fuel pump relay. The single problem I have is a lack of 12v energisation of the fuel pump relay when either priming or attempting to start the car.

Every fuse including the maxi fuse in both fuse panels has been checked for continuity and tested okay.

Vats programming seems to be succesful, the car recognises the key etc and the security light seems to work as it should (flases when door is open, goes off when I start the car or put the key in the ON position etc)

The car hasn't been submerged, nothing has been under water. All the electronics are dry and in good order except for the original PCM which had water ingress through the connectors.

I hope that makes things clearer!

I believe my issue is either related to the serial data comms or BCM... Or, possibly the BCM needs to have the relearn procedure carried out due to the PCM being replaced (even though it seems okay) Open to ideas though!

 

[Stingray]

teamZR1 - am I recalling correctly that the infamous C5 steering column lock failure would, amongst other things, shut off the fuel pump?

I wonder what's the column lock status of Llewellyn's car? When my C5 failed GM's official dealer in UK was unable to get it going even after contact with GM HQ in the US. Eventually GM US said, "stick a column lock bypass on it and see if that works". The official dealer had no access to the unofficial part so I sourced one via Eurovettes in UK and it was fitted by the dealer. Problem fixed.

 

[Llewelyn]

teamZR1 - am I recalling correctly that the infamous C5 steering column lock failure would, amongst other things, shut off the fuel pump?

I wonder what's the column lock status of Llewellyn's car? When my C5 failed GM's official dealer in UK was unable to get it going even after contact with GM HQ in the US. Eventually GM US said, "stick a column lock bypass on it and see if that works". The official dealer had no access to the unofficial part so I sourced one via Eurovettes in UK and it was fitted by the dealer. Problem fixed.

Thanks - As I understand it looking at the wiring diagrams in the service manual the steering column lock prevents power to the fuel pump relay if the vehicle speed exceeds 2 mph but wouldn't stop the car from starting and idling. I could be wrong though, I am by no means an expert!

Mine for clarification has a steering column lock bypass fitted.

 

[teamzr1]

Only focus of my image below

Fuse 13, 20 Amp goes to 4 pin relay in fuse panel,
The coil of relay switches that 12 volts on and off to fuel pump
So one side of the coil goes to ground, assure it is ground
Pin 9 of red connector of PCM is what controls the COIL being on or off,
When PCM commands that side of coil to engage then should have 12 volts to fuel pump, left one

So if you verify you have ground, 12 volts from fuse 13, and when you jumper the relay then the fuel pump becomes active

That still to me says the control from PCM to relay has to be tested and checked out

Is it possible the wiring pins in the fuse panel for that relay have pushed downwards, so cannot make contact with pins of the relay ?
Possible the wiring pin from PCM is bad, such as weak crimp of that PIN

As mentioned, odd crap happens with weak grounds, did you check the main engine ground on back of LEFT head by firewall that goes to frame ?
And assure ground of coil is good ?

Focus on PCM pin 9 of wiring, I mentioned and got no answer from you
IF cranking engine, and you have a meter on the wiring pin (relay taken out) socket for relay, does it change state when cranking and when not ?