Is it possible to retrieve ccm codes with scan tools, or do you need tp use the dlc and fuel/mileage panel?

I recently purchased a 90 6spd and the sys light flashes. Normally this wouldn't be a problem yet the buttons for displaying average fuel economy and such decided not to cooperate with me. The inflatable restraint light is constantly illuminated as well as the seat belt light. Underhod lights do not work, as well as cruise control. Rarely it decides when I turn the key to start that it does not want to do anything but run the dash. I bought hte care thinking it was a miswired alarm system. The alarm guys told me that the data bus line is somehow tied in to hte dimming controls for hte factory radio for which I do not posess. Is that true as well...won't have wiring diagrams for a few days.

Thanks for anyhelp you guys can give me

 

The data bus is not directly tied to the dimming which is driven by the CCM. The Sys light indicates the CCM found a fault, one of which is the dimming circuit. The wiring diagam will show the signal. There are posts here that show how to fix that prolemby adding a resistor if that is the only CCM problem. Some of your other problems are not related to the CCM. The air bag system is completely independent of the CCM and is not on the serial data bus.

I do not have the manual with me (on TDY) but I am sure others will answer the interconnect of the ECM, CCM, ABS, and HVAC computers.

 

Pulling CCM and ECM codes can be done with a paperclip inserted into specific pins in the ALDL located at the right corner of the knee bolster just above where your knee is when sitting in the car. Try doing a search on ECM codes or pulling codes.

The SIR light is a common occurance with the 90 C4. It is usually because of a bad ground contact on one or both the air bag sensors. There are two sensors mounted on the frame. One is under the A/C housing on the firewall and is usually the problem due to condensate dripping on the sensor and rust forms where it attaches. There is a tech tip on fixing this problem. The seat belt light can be related to the SIR problem.

The hood lights are probably disconnected. Follow the wire from the lights to connectors near the side marker lights and ckeck to see if they have been disconnected. Lots of folks do this when the hood is open for long periods of time and keeps the battery from draining.

The SYS flashing on the display is probably due to an incorrect installation of a non factory radio. Check the tech tips for solving this or try searching in the Audio section of teh Forum. This is another common problem but the SYS light can also indicate a bad charging system or component (battery, alternator).

Cruise control issues can be a variety of things. Bad cable, fuse, bad disengage switch at the brake or clutch pedal or the control on the stalk.

One of the best investments you can make is to buy a factory GM service manual. Go to the Helm website at www.helminc.com and order one. It's the same manual the GM service techs use and is definitely worth the money if you are going to do some of your own work or have it available to whoever does work for you.

 

email me. I have a doc that will walk you through it.

 

Thanks for the help. I work at a small independent shop, just graduated from a 2 year auto tech program. This is my first vette so I am getting used to all the new thinga-ma-bobs and du hickies. I just bought it a few days ago. I believe it is teminals a and g that you jumper however with out use of the buttons to navigate the codes, that is my dilemma.

 

sorry had a problem with my browser...incase my email didn't make it is erichards5@cfl.rr.com....browser is sick too apparently