MITCH

I have a 1989 C4 and keep getting a code 36 but not all the time.
The old owner put in a mass air sensor last year and i have changed the relays and cleaned all the connections.
This is what happends i reset the light and i can drive the car for hours with no light or drivably problems.I park the car and restart and i get the light again. I reset and it comes back but not right away. Car runs fine with or without light on.
Need some I ideas??
1989 c4
L98 6speed
chip for early fan turn on other wise stock.
Thanks for any help!!
Mitch

MITCH

top!!

vetteoz

Do the system diagnostics.
A code indicates a fault SOMEWHERE in a system ;
not that the items of that system are themselves faulty
Could be a power, wiring , connection or ground problem

http://www.chevythunder.com/maf_code_36.htm

MITCH

Thanks for the info.I will look at it this weekend again.
Mitch

guno89

In my 89 I ended up swapping out the MAF burn off relay and the code 36 went away. I know you mentioned you replaced the relay, I had this happen 2x I bought relays from autozone and ended up not working. I then got Napa relays and the codes wen't away.

Cliff Harris

I wrote all this out last night and then the Forum went offline and I couldn't post it...

Error code 36 is a MAF burnoff fault. Burnoff only happens when you turn off the ignition, so you will never see a problem while driving.

The ECM controls the MAF burnoff. It only goes through a burnoff cycle if the ECM is in closed loop mode when the ignition is turned off. That unfortunately prevents you from turning the ignition on and off and on and off to troubleshoot.

When the ignition is turned off the ECM turns on the MAF burnoff relay (or the MAF burnoff module in '85s). That applies 12 volts to the MAF sensor wire, which will cause it to glow red for about 1 second. During the burnoff cycle the ECM monitors the voltage coming out on the MAF sensor wire. The voltage must be between 0.4 volts and 1.9 volts or the ECM will set an error code 36. All this happens pretty fast so it's kind of hard to actually measure the voltage. What I have done is put a mirror in front of the MAF and watched the wire glow after I turned off the ignition. The MAF has to be attached to the throttle body to make this work.

The possibilities are:

The ECM is not turning on the MAF burnoff relay. The could be something happening inside the ECM or the wiring, connectors, or relay is bad.
The MAF burnoff relay contacts are bad and not applying the 12 volts to the MAF.
The wiring or connectors between the burnoff relay and the MAF are bad. 12 volts might not be getting to the MAF burnoff relay.

You should be able to turn off the ignition and hear the MAF burnoff relay go clickety-click (if your ear is close enough).

All this would be much easier if you had one of these MAF testers, but as far as I know this is the only one in the world (sometimes it's handy to be an electronic engineer):



It was made from this guy, which you can buy from Mid America:

http://www.mamotorworks.com/Corvette...-tool-601096-1

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