scrambled LCD data and inoperative C68 controller only when engine runs
05-10-2024, 03:20 PM
#1
4th Gear
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scrambled LCD data and inoperative C68 controller only when engine runs
Hello everyone,
I have troubling symptoms on a C68-equipped C4 corvette, and I wanted to have your expertise to understand what could be the possible culprit.
The symptoms: (see
)
- When key in run position (engine off), the climate controller (C68) is working fine , I can use all buttons, read all parameters etc (I have the FSM).
- When engine runs, the C68 displays "---" (serial data error according to FSM), no buttons are working. The LCD display of the dashboard is sometimes displaying scrambled data.
Of course, everything was working perfectly fine 6 months ago, prior the car got stored for the winter...
What I have ruled out:
- bad grounds (G106 and G201 thoroughly cleaned and reassembled)
- overvoltage (did try without the alternator hooked in and same issue - voltage is max 14.6V with alternator)
- checked all pins on the C68 controllers for voltage as per FSM.
- C68 controller unhooked (and the dashboard's LCD displays scrambled data as well)
- main dashboard unhooked (and the C68 controller will not work when engine runs).
I therefore wonder if the problem comes from the CCM or the C68 programmer, but I have a hard time understanding how it would run fine when engine off and not when the engine is running ...
I have not read anyone having had similar symptoms as far as I can recall.
If you any idea of what further tests I can do outside what the FSM tells me, I would appreciate!
I have troubling symptoms on a C68-equipped C4 corvette, and I wanted to have your expertise to understand what could be the possible culprit.
The symptoms: (see
- When key in run position (engine off), the climate controller (C68) is working fine , I can use all buttons, read all parameters etc (I have the FSM).
- When engine runs, the C68 displays "---" (serial data error according to FSM), no buttons are working. The LCD display of the dashboard is sometimes displaying scrambled data.
Of course, everything was working perfectly fine 6 months ago, prior the car got stored for the winter...
What I have ruled out:
- bad grounds (G106 and G201 thoroughly cleaned and reassembled)
- overvoltage (did try without the alternator hooked in and same issue - voltage is max 14.6V with alternator)
- checked all pins on the C68 controllers for voltage as per FSM.
- C68 controller unhooked (and the dashboard's LCD displays scrambled data as well)
- main dashboard unhooked (and the C68 controller will not work when engine runs).
I therefore wonder if the problem comes from the CCM or the C68 programmer, but I have a hard time understanding how it would run fine when engine off and not when the engine is running ...
I have not read anyone having had similar symptoms as far as I can recall.
If you any idea of what further tests I can do outside what the FSM tells me, I would appreciate!
05-10-2024, 06:29 PM
#2
Safety Car
Did you clean all of the contacts on the controller?
Also try disconnecting the battery for 10 minutes.
Also, do not try starting the engine from the accessory position as you did in the video.
Hope this helps.
Manny
Also try disconnecting the battery for 10 minutes.
Also, do not try starting the engine from the accessory position as you did in the video.
Hope this helps.
Manny
05-13-2024, 01:21 PM
#3
4th Gear
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Hello Manny,
thanks for your inputs, yes I did use electronic connection cleaning spray on both the dashboard pins and the C68 controller plug.
For the battery, tested as well - there is a battery quick disconnect I use whenever the car is planned to stay still for a few days or more.
I tried with starting "directly" the engine, same issue :-(
The CCM is utterly badly placed in the car to get hold of it, so maybe I should try disconnecting the C68 programmer first? There is definitely a serial-connected device sending gibberish data on the line...
thanks for your inputs, yes I did use electronic connection cleaning spray on both the dashboard pins and the C68 controller plug.
For the battery, tested as well - there is a battery quick disconnect I use whenever the car is planned to stay still for a few days or more.
I tried with starting "directly" the engine, same issue :-(
The CCM is utterly badly placed in the car to get hold of it, so maybe I should try disconnecting the C68 programmer first? There is definitely a serial-connected device sending gibberish data on the line...