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C5 starting issue

Andy1B

CCCUK Member
I have a 2003 C5 auto. It's been off the road during the winter but I've started it, warmed it and run it down the road every few weeks.
Now, on turning the ignition I just get a click from a relay but the starter motor doesn't turn. Battery is fully charged but I've also connected jumper leads from another car (with engine running).
The click appears to come from the module adjacent to the instrument fuse block in the passenger footwell. It doesn't sound like the click of the solenoid engaging; it's lighter than that. When turning the key to start the voltage meter goes way down but comes straight back to 12+ volts when I release the key. It's as though the starter pinion is already engaged but, being auto, I can't put it in gear and rock the engine to free it. I tried to turn the engine with a socket on the crankshaft pulley but there's a chassis rail in the way!!!
Does anyone know if this is a known problem with a known solution or do I need an auto electrician? If so, can anyone recommend someone in Essex? Preferably near Chelmsford/Witham/Maldon?
 

teamzr1

Well-known user
  1. Did you keep the battery on a tender over the cold months ?
  2. Have you done a battery load test ?, should be more like 13 volts
  3. When you open the door does the security light on dash flash ?
  4. Go into Diag mode via the DIC and report here all the error codes it shows
  5. You sure the battery does not have a bad cell ?
  6. Have you tried the spare Ign key to see if the one you have been using has a dirty VATS resistor or it is bad ?
  7. With key ON can the steering wheel be turned ?

Just in case the controllers are out of sync on the Starbus network and cannot talk to each other

Take the 2 main battery leads off battery
and use a bare wire to tie the 2 leads (shorting them together) together for like 15 minutes
this will cause all controllers to erase any error conditions ( get the DTCs (errors ) written down BEFORE doing this

If battery is in fact good and fully charged it could be VATS (security ) or column lock relays having a problem
What I do as these are normal failures for my customers is I turn off VATS, limp mode and column lock
so they never can cause a no start condition
 

PhilV8

CCCUK Member
Had a similar thing with my Cadillac, got the local garage to test it..... Their gadget said 'replace battery' which I did and car is fine. Strange thing was you could leave the car overnight and it would start..... just
 

Andy1B

CCCUK Member
  1. Did you keep the battery on a tender over the cold months ?
  2. Have you done a battery load test ?, should be more like 13 volts
  3. When you open the door does the security light on dash flash ?
  4. Go into Diag mode via the DIC and report here all the error codes it shows
  5. You sure the battery does not have a bad cell ?
  6. Have you tried the spare Ign key to see if the one you have been using has a dirty VATS resistor or it is bad ?
  7. With key ON can the steering wheel be turned ?

Just in case the controllers are out of sync on the Starbus network and cannot talk to each other

Take the 2 main battery leads off battery
and use a bare wire to tie the 2 leads (shorting them together) together for like 15 minutes
this will cause all controllers to erase any error conditions ( get the DTCs (errors ) written down BEFORE doing this

If battery is in fact good and fully charged it could be VATS (security ) or column lock relays having a problem
What I do as these are normal failures for my customers is I turn off VATS, limp mode and column lock
so they never can cause a no start condition
Thanks for this good info. I'm now away for a few days but will go through this on my return.
At first (since November) I just started it every couple of weeks and ran it down the road. Then I left it longer and the battery went flat, obviously draining over time. I then charged it, started it etc. So then I disconnected the battery when I left the car and every couple of weeks I connected it, started etc and it was fine. I trickle charged the battery as well. It's only this last occasion, with the battery fully charged, that the engine is not turning over, just a click from the module next to the internal fuse block.
Re your questions, I trickle charged the battery occasionally to keep it topped up. I haven't done a test but the dash gauge shows over 12V, when I turn the key it goes down but returns to 12+V when I release the key. With the battery connected an alarm chimes when I open the door but I haven't noticed a dash light. (I must take more notice!). I haven't tried the spare key but will when I get back. The steering wheel lock had been immobilised before I got it. I understand it was a C5 problem.
I'm a Vette newby. I've heard about checking the codes but don't know how to go about it. Could you guide me through it?
Thanks again. I'll do the above next week.
 

teamzr1

Well-known user
Really sounds like battery has one or more weak cells, and not about voltage level but battery
not able to handle current loads.

To check if and what error codes there may be

1. Turn your key to the "ON" position, but do not start the engine.
2. Clear any present messages on DIC by pressing the RESET button.
3. Hold the OPTIONS button down, and press the FUEL button 4 times.
(This will get you into the "codes" section of the DIC)
4. The computer will automatically display all the codes your car has created.
It will cycle through each code every 3 seconds. (write down any codes shown)

Note: Any code that ends in an "H" is a history code (something that has occurred in the past, or C which means current)

5. Once the computer has finished going through all of its codes, press RESET to enter Manual Configuration mode.
It should start with a module and show "NO CODES" or "# Codes."
6. To optionally reset codes once in manual mode, press and hold RESET until is displays "NO CODES."
7. Press OPTIONS to go into the next module (ie, from PCM, or Powertrain Control Module, to TCS, or Traction Control System.)
8. Repeat Step 6 until you have reset all the codes in all the computer modules.


Not good to leave battery off due to age of car in that the controllers talk to each other via the Starbus network
so there is a chance when battery back on one or more controllers do not sync up on network

As example for engine to start the PCM (powertrain controller module) and the BCM (body chassis module) need to
exchange the VATS (security) code and if cannot then engine a no start)

Might be a good idea to open the hatch door on passenger floor, that is where the BCM, Starbus and fuse panel is
and make sure all wiring connections are firmly plugged in or some mouse, etc not eating wiring
 

oelarse

Regular user
That click you are hearing is probably from the Theft Deterrent Relay ,located close above the BodyControlModule in the passenger footwell .
You may have a starter solonoid issue .
First you should check if Fuse 52 (60A ) is OK . If it is ok you will measure 12 on the C1 terminal of TDR relay shown below .
If the TDR relay works OK you should measure 12 volt on the purple wire going from relay to the starter solonoid when you try to start the car .

If you got 12 volt on the starter solonoid (purple wire) and the starter solonoid does not operate , it sometimes helps to give the starter solonioid a hard knock with a hammer or similar .
I advise you to disconnect your battery in front of this because if you try this trick

Hopefully the starter solonoid will start working for some time , but you should replace it asap .

The photo below is from my starter ( 00 model) when I replaced my balancer last year and you can see the purple wire.






3381

3384


3383
 

Andy1B

CCCUK Member
Really sounds like battery has one or more weak cells, and not about voltage level but battery
not able to handle current loads.

To check if and what error codes there may be

1. Turn your key to the "ON" position, but do not start the engine.
2. Clear any present messages on DIC by pressing the RESET button.
3. Hold the OPTIONS button down, and press the FUEL button 4 times.
(This will get you into the "codes" section of the DIC)
4. The computer will automatically display all the codes your car has created.
It will cycle through each code every 3 seconds. (write down any codes shown)

Note: Any code that ends in an "H" is a history code (something that has occurred in the past, or C which means current)

5. Once the computer has finished going through all of its codes, press RESET to enter Manual Configuration mode.
It should start with a module and show "NO CODES" or "# Codes."
6. To optionally reset codes once in manual mode, press and hold RESET until is displays "NO CODES."
7. Press OPTIONS to go into the next module (ie, from PCM, or Powertrain Control Module, to TCS, or Traction Control System.)
8. Repeat Step 6 until you have reset all the codes in all the computer modules.


Not good to leave battery off due to age of car in that the controllers talk to each other via the Starbus network
so there is a chance when battery back on one or more controllers do not sync up on network

As example for engine to start the PCM (powertrain controller module) and the BCM (body chassis module) need to
exchange the VATS (security) code and if cannot then engine a no start)

Might be a good idea to open the hatch door on passenger floor, that is where the BCM, Starbus and fuse panel is
and make sure all wiring connections are firmly plugged in or some mouse, etc not eating wiring
Thanks so much for this good info. Confirming answers to your previous post, when I open the door the chime sounds and the Security light flashes. The spare key doesn't work either, and the steering wheel can be turned at all times. ( I bought the car last summer and it's always been like that).
Re the codes, I had 24 all together, mostly history but 3 in the "40 BCM" part had a C: B0432, B0502 and B0507.
After checking I cleared all codes in each module, or at least I tried to. The 3 current codes stayed as did two History codes in the "A0 LDCM" part. These were B2262 H and B2264 H. Both stayed even though I tried to clear them 3 times.
Also, "A6 SCM" said No Comm. Presumably no communication, but I don't know what SCM means.
Finally, I tried your other suggestion and tied the two battery leads together for about half an hour. When I reconnected the battery I still have the fault and I checked the codes again. The three current codes are still there on the BCM and the two history codes are still there on the LDCM.

So, thanks for the guidance so far but clarification of the codes and any further advice would be very welcome. I'm about to do the solenoid checks suggested in another reply to this thread.
 

FIVE RED

CCCUK Member
Looking at my book of codes I've found these descriptions:
B0432 - rear defogger relay circuit
B0502 - RH DRL relay circuit
B0507 - LH DRL relay circuit
B2262H - horizontal position sensor fit
B2264H - vertical position sensor fault
A6SCM - seat control module

So there you go, good luck
 

teamzr1

Well-known user
You mention there was 24 DTCs before clearing codes, some may return again, they could be "U" codes
which are comm DTCs as controllers not being able to talk to each other on the Starbus network
What codes your showing are mostly for

  1. B0432 Rear Defogger Relay Circuit
  2. B0502 control for the Right Daylight Running Lamp (DRL) relay circuit
  3. B0507 LH DRL Relay Circuit
  4. "A0 LDCM" part. - means Left Door module
  5. B2262-B2265 Mirror Position Sensor Signal Circuit
Also, "A6 SCM" said No Comm - Seat Control Module
Presumably no communication, but I don't know what SCM means.

None of those would cause a no start condition
Try starting again multi times and then check to see if any new DTCs trip

If no no DTCs then problem is something the controllers cannot monitor such as a weak battery,
Bad grounding or other wiring issues
I would open the floor hatch on passenger side to get to the BCM, fuse panel and all the Starbus wiring
and look for wiring issues, or Starbus connectors not fully seated in and if Ign switch wiring and when in start mode if
voltage is then to starter and PCM commanding fuel injectors on
Also check oil pressure sensor as if it or its wiring has a problem PCM will not allow engine to start to protect the engine
 
Last edited:

FIVE RED

CCCUK Member
Just looking at the various descriptions it occurs to me that you may be suffering from some bad earths, a fairly common problem on C5's. Not hard to fix once you've found the earth points but there are quite a few. The subject has been covered on here before I recall.
 

FIVE RED

CCCUK Member
The above is a useful diagram to print off if anyone is suspecting earth problems. Just adds to the fun of C5 ownership.
 

teamzr1

Well-known user
Other info
Ign switch
Clean Ign Switch

Grounds locations
Grounds

Ground splice packs are square in shape
As example look on frame by battery, you see several ground wires going into it
the cover comes off that pack, hard to come off, clean all connections of wires and the underside of pack

There is a opening for right front inner-fender (back side of it), it comes off and behind it is the PCM and all that wiring
Check for bad wiring, maybe battery leaked acid and eat wiring or some mouse, etc got in and eat wiring
 

oelarse

Regular user
I removed my PCM and Tach module a couple of years ago and it looked like this . It was only a cleaning and repainting job , but several people has got into major problems when the acid from battery has into the PCM wiring mentioned above. Every one with a C5 should take a look below the battery or inside front right wheelhouse .
Regarding the Seat Control Module ,there is one under both seats .
Are both seat operating ? If not you should first check the fuses are OK .
I leave schematics for both seats below the photo
3414

3415

3416
 

Andy1B

CCCUK Member
That click you are hearing is probably from the Theft Deterrent Relay ,located close above the BodyControlModule in the passenger footwell .
You may have a starter solonoid issue .
First you should check if Fuse 52 (60A ) is OK . If it is ok you will measure 12 on the C1 terminal of TDR relay shown below .
If the TDR relay works OK you should measure 12 volt on the purple wire going from relay to the starter solonoid when you try to start the car .

If you got 12 volt on the starter solonoid (purple wire) and the starter solonoid does not operate , it sometimes helps to give the starter solonioid a hard knock with a hammer or similar .
I advise you to disconnect your battery in front of this because if you try this trick

Hopefully the starter solonoid will start working for some time , but you should replace it asap .

The photo below is from my starter ( 00 model) when I replaced my balancer last year and you can see the purple wire.






View attachment 3381

View attachment 3384


View attachment 3383
Thank you so much for this. When it first happened it felt like the starter was stuck in. The voltage goes way down when I turn the key to start but no sound from the starter, just the click in the footwell. If it had been a manual I would have put it in gear and rocked the car to try to free it but not with an auto..... Anyway, the fuse is OK and now I know about the TDR I can feel that unit click when I tun the key. So I'm pretty sure you're right it's the starter or solenoid but the problem is how to get a hammer to it. I can't even find it!!! OK, I haven't got the jack out yet to get under it but I can't even see it from above. I see in your photo that the exhaust manifold is disconnected. Is that necessary to get at it? Frustratingly I'm away from home for a few days now but will get back on this next week and let you know.
 

Andy1B

CCCUK Member
Looking at my book of codes I've found these descriptions:
B0432 - rear defogger relay circuit
B0502 - RH DRL relay circuit
B0507 - LH DRL relay circuit
B2262H - horizontal position sensor fit
B2264H - vertical position sensor fault
A6SCM - seat control module

So there you go, good luck
Thanks for this. At the moment both seats are out while I'm trying to fix various leaks and dry the carpets.
I don't really understand many of the abbreviations used (DRL?) or what the horizontal and vertical position sensors refer to. Is there a place, web-site or link to this code info?
 

Andy1B

CCCUK Member
I removed my PCM and Tach module a couple of years ago and it looked like this . It was only a cleaning and repainting job , but several people has got into major problems when the acid from battery has into the PCM wiring mentioned above. Every one with a C5 should take a look below the battery or inside front right wheelhouse .
Regarding the Seat Control Module ,there is one under both seats .
Are both seat operating ? If not you should first check the fuses are OK .
I leave schematics for both seats below the photo
View attachment 3414

View attachment 3415

View attachment 3416
Thanks for this too. At the moment both seats are out while I'm trying to fix various leaks and dry the carpets but a couple of the movements on the drivers side were not working. I had read bout dry solder joints and a friend went over the seat circuit boards with a soldering iron but it made no difference (in fact worse so I swapped the working passenger mechanisms for the non-working drivers ones). Your circuit diagrams may help if/when I have another go.
Re the PCM and battery, that's on my to-do list.
 

Andy1B

CCCUK Member
You mention there was 24 DTCs before clearing codes, some may return again, they could be "U" codes
which are comm DTCs as controllers not being able to talk to each other on the Starbus network
Yes I had U1064 on both LDCM and RDCM, and on SDM I had 5 U codes; 1000, 1016, 1040, 1064 and 1096
What codes your showing are mostly for
  1. B0432 Rear Defogger Relay Circuit
  2. B0502 control for the Right Daylight Running Lamp (DRL) relay circuit
  3. B0507 LH DRL Relay Circuit
  4. "A0 LDCM" part. - means Left Door module
  5. B2262-B2265 Mirror Position Sensor Signal Circuit
Mine was a US import and the standard DRLs have been disconnected and replaced by LEDs. Could this be why these faults are showing?

Also, "A6 SCM" said No Comm - Seat Control Module
At the moment my seats are out while I'm trying to fix various leaks and dry the carpets.
Presumably no communication, but I don't know what SCM means.

None of those would cause a no start condition
Try starting again multi times and then check to see if any new DTCs trip
I will check the earths but what do you think of another reply suggesting the starter or solenoid is stuck in? This would explain why the voltage drops when I turn the key to start. I've also confirmed that the click I can hear is from the Theft Deterrent Relay in the passenger footwell. I need to get to the starter to either remove it or try losening and/or clouting it!

If no no DTCs then problem is something the controllers cannot monitor such as a weak battery,
Bad grounding or other wiring issues
I would open the floor hatch on passenger side to get to the BCM, fuse panel and all the Starbus wiring
and look for wiring issues, or Starbus connectors not fully seated in and if Ign switch wiring and when in start mode if
voltage is then to starter and PCM commanding fuel injectors on
Also check oil pressure sensor as if it or its wiring has a problem PCM will not allow engine to start to protect the engine
 
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