Smog/Secondary fan and HVAC issues

Mick Howes

CCCUK Member
Still trying to sort out this problem, strange thing is, it seems to be becoming intermittent, at times the SES warning doesn't come on for several minutes, then back again. During the times the SES lamp is off, the main fan also stops (it always comes on when there is a Smog pump fault) Could anyone let me know where the electrical connections etc (other than at the plug on the fan/pump) are, hoping there may simply be a loose connection somewhere else.
Of course once I get this sorted, still got the bloody HVAC problem, nothing works, the display unit illuminates but no actual displays and nothing works, AC, fans, Heater Control etc etc. I have checked the 4,000 fuses than control the system, even replacing fuses that don't appear blown, nothing fixes it! As the display actually illuminates, I assume there is definitely power going to the HVAC unit.
If only I lived in the South East UK I could go to one of the many Corvette centres, sadly cannot find anywhere here in Somerset!
 

teamzr1

Supporting vendor
What year is your C4 ?
If 1990 to 1995 C4, do you have an OBD-I scanner, as it would be very helpful in debugging the issues you're having ?

The scanner would show exactly what DTCs are being tripped and also as example if the A/C system is being commanded on
like this one I use

c4ac.jpg

If no scanner if shorting certain pins of the ADLC will show DTCs tripped
Too lengthy to post here, but all that info to do this you can read on a post I did on my forum many years ago at :


Behind the radio is the CCM (Central Control Module) which handles all non engine functions like the HVAC head
Make sure it is getting voltage and good ground
 

Mick Howes

CCCUK Member
Thanks, it's a 95, this is the one you tried to sort the ECM problems caused by the idiot who screwed up everything trying to remap to switch off the Smog pump, in the end I had to get a new ECM from Davies Corvettes in New Port Richey (who were really helpful) they programmed it to my car's VIN, plugged in and car started straight off, however the Smog pump problem still exists, even after installing a new unit. Also the HVAC not working, must be voltage going to the unit as the display lights up, just nothing (figures etc) displayed. Whatever the idiot did caused an issue somewhere within the HVAC unit too. I still use the car as much as possible, my only worry is that as the main fan comes on when the SES shows, I am not sure how long an electric fan will keep running before it burns out, the main fan only meant to come on when required to cool, not run permanently.
 

teamzr1

Supporting vendor
This cannot be solved without knowing what error codes are tripped and use an OBD scanner or as I mentioned
use my forum link to show how to jumper the ADLC and report here what the codes are
I still think you need to look at all ground locations for dirty, bad ground points

If coolant fan is coming on then need to see what the coolant temp gauge is showing
and again with a OBD scanner would be able to show if the ECM is commanding the fan on or not

SMOG, have you tested by taking out the fuse for that pump, or its relay ?

HVAC might not work if the coolant temp is faulty or, as I mentioned, if the CCM is at fault or the ECM

But all guessing by not investing with an OBD scanner and let the controllers says what the problems are
 
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