My C4 is a triple black 87, with 64K miles. Ive had this car for 2 years and love it (what Vette owner doesn't love his Vette). It had 2 small problems, the center display Service Engine light is on most of the time. it indicated MAF malfunction so I replaced the Mass Air Flow. This did not solve the problem. I then found a service bulletin page that indicated that it was probably the relay, here is a copy of the bulletin.

Service Bulletin Number: 87-270-6E
Bulletin Sequence Number: 031
Date of Bulletin: 8801
NHTSA Item Number: 98253
Make: CHEVROLET
Model: CORVETTE
Year: 1987
Component: ELECTRICAL SYSTEM:IGNITION:ELECTRONIC CONTROL UNIT
Summary: MASS AIR FLOW (MAF) SENSOR SYSTEM DIAGNOSIS CODES 33/34 AND 36-MAF POWER RELAY S HOULD BE P/N 10067925-IF NOT REPLACED WITH P/N 10067925-ALL 1986 TO 1987 CHEVROL ET CAMARO AND CORVETTE MODELS WITH 5.0L OR 5.7L PFI ENGINES

Where is this relay located on the car?

The 2nd problem is the low coolant light is on and off. I found another bulletin that stated to replace the sensor and tighten a hose. After doing this I still have the same problem although the coolant is full and the temp while driving is in the normal 185-195 range. This car runs great but the lights are annoying. Any help is greatly appreciated.

 

the relays are on the firewall... where, I can't help ya, because on my wifes 87, the chuckleheads who put it back together after it was stripped at a chop shop moved them to the inner fender well.

it is advised to replace both MAF relays when replacing the maf. you really need to invest in the Helm service manual, www.helminc.com.

The low coolant light is a problem... it is mounted high on the radiator and is prone to false readings. You can replace the sensor, and it might help for a while... but if the coolant IS low, then be sure the headgaskets or intake manifold gaskets are good.

 

I had the same problem when I bought my '87 coupe. The MAF relays (there are two of them) are located behind the battery. One is the "burn-off relay" and the other is the "power relay". Replace both of them.
The low coolant light is a common problem. Its caused by air trapped in the system. There used to be a post in the "search" section describing how to "burp" the system. My low coolant light still flashes on once in awhile. I just ignore it because I know there is really nothing wrong.

 

Also check out the wiring and connectors per the troubleshooting procedure. A little bit of time and effort can save you a bunch, not buying unneeded parts.

 

both are behind the battery on the firewall, together they are about $25

then i would burp the system to make sure its full when the stat opens

 

Thanks everyone getting ready to work on it now.