AlexJH

I'm trying to track down a code 36 on my 89 L98.

A while ago there was a post that detailed how to troubleshoot MAF wiring, and I bookmarked it, but it's disappeared with the changeover to the new BB software.

It was a step by step process, ie; with the key on, engine off, check the voltage at pin 3 of the MAF relay, and so on.

Does anyone have this post or know how I can find it in the archives?

Thanks.

Swapmaster

This is for code 33 and 34 but will trace the MAF wiring for you.

Code 33 tests.

First check air ducts for cracks, holes and tighten clamps.

With the ignition off, unplug the MAF and apply power to ALDL terminal
"G". Check the red wire on the MAF connector for power. If no power,
verify 12v on relay connector orange and white/tan wires. Verify the
connector black/white wire is grounded. Verify black wire from MAF
connector terminal B to ECM connector A11 with an ohm meter. Verify
red wire from relay connector to MAF connector with an ohm meter.
If all is good replace MAF power relay.

Turn ignition on, Check MAF connector dark blue wire for 12v, if so,
unplug MAF burn off relay and check again. If so, check relay
connector black wire for ground. If so, the black wire is shorted to
ground or the ECM is bad. If not, replace MAF burn off relay.

If the dark blue wire at the start of the above test had no voltage,
check the MAF connector dark green wire with ignition on for a 5v
reference signal. If so, and all connectors are good, replace MAF.
If no 5v reference on dark green wire, verify it from the MAF connector
to ECM connector B12 with an ohm meter. If the wire is good replace the
ECM. If the dark green wire has 12v on it, turn ignition off and unplug
the ECM connectors. Turn ignition back on and check again, if so,
it is shorted to power somewhere. If not, and all connectors and
grounds are good replace ECM.

This test will also repair code 34

Swapmaster

Here, this should do it.

Code 36 test.

Clear codes.
Ground diagnostics terminal.
Start engine and wait for the check engine light.
Unground terminal.
Shut off car.
Wait a minute or so.
Restart car for 20 seconds or until check engine light comes on.
Shut off car.
Turn ignition to ON position
Check for codes.
No code, problem intermittent.
Code 36, unplug burnoff relay, check both orange wires for power.
If one or both have no power, repair open circuit.
If both orange wires have power, reconnect relay.
Disconnect MAF sensor.
Ground burnoff relay black wire, terminal "F".
Check MAF connector terminal "D" for power.
If no power, replace burn off relay.
If it has power, with relay terminal "F" still grounded, check MAF
plug terminal "E".
If no power, replace MAF power relay.
If terminal "E" has power, disconnect burn off relay.
Check burnoff relay black wire (terminal "F") for power.
If it has power it is shorted to power somewhere.
If it has no power, suspect ECM or ECM connector.
Code 36 can be caused by a bad connection at either relay.
Check relay connector contacts for corrosion and tight fit before
replacing ECM.

AlexJH

Aha, that's it. Thank you!!! Where did you find this info?

Swapmaster

A trouble shooting manual I got years ago.
And no, you cant buy one anywhere.

Matt87GTA

Looks a lot like a summerized T-shooting tree from my GM service manual .

Swapmaster

That's what it is.

AlexJH

<grin>

When I went to unplug the MAF connector, I noticed one of the pins on the plug was screwed up... terminal E. I bent it back in place and it seems to work now. Heheh.

Thanks though, that post helped me figured it out.

Swapmaster

KOOL

Vader

Swap,

I hope you don;t mind, but I just "stole" that troubleshooting trr from you. It would save one helluva lot of typing.

Swapmaster

Well the two trees above cover codes 33, 34 and 36.
I will likely post more when and where necessary, so
keep your eyes open.

I save the condensed copies myself. Sometimes trees
can get confusing when they get 3 or 4 tiers out.

waltersb

I have an 89 so my MAF connector only has 5 terminals...

how do you ground the black wire from the MAF burnoff relay causing the ECM to trip the MAF burnoff?

I don't have a terminal F as listed on the troubleshooting above etc.....

So what am I grounding???

Guest

Low cranking voltage can trip off a code 36 as well.

waltersb

Well I managed to get a wire into the gap between the wire and the connector on the ECM and low and behold the relay tripped...

and gave the results it was supposed to...

Problem I'm having is that the 36 shows up periodically...

I was driving on the highway at like 75mph it went on, and then promptly went back off..

no codes..

It seems to show up after some travelling..

Guest

Didnt realize how OLD this post was... then it got locked, unlocked, here it is. Thats what I get for not reading dates...

All the TPI MAF's have 5 wires.

Weird that you are getting a 36 while driving, almost sounds like a loose wire or ground thats making it think the engine is off or something like that. Check the wiring, make sure none of them are cut or frayed and touching metal or each other. Near the relays the wires are notorious for melting the insulation down off where it used to be, leaving a bunch of exposed wire right near the connector. Maybe thats a problem on yours as well. The right bump or rush of air might just be enough to trigger it and set the code.

At the MAF connector itself is also a place where the connection can be bad, either bent/damaged pins on the MAF or a worn out plug on the wiring side.