AJ123

New Maf

Tested my MAF on a friends 87 vet he pulled no codes. Put his on mine still came back 36.
Messed with wires cleaned plug. No go. I start by clearing code. Will start up and run all day with no code. Shut it off re start and the code comes back up. I have already replaced the relays.
Will have a new plug here Friday. I wasn't going to pay 50 bucks from CARQUEST.
Any suggestions

AJ123

bump

Cliff Harris

Error code 36 is a BURNOFF fault. That test is only done AFTER the ignition is turned off. The burnoff relay applies 12 volts to the MAF sensor wire and the ECM checks the output from the MAF while this is happening. If the output is not within the parameters it sets error code 36.

There are two MAF relays mounted on the firewall behind the battery. One is the MAF power relay and the other is the MAF burnoff relay. They have the same part number and you can swap the connectors and see if the problem still exists (this is true for '87 and later cars. On the '86 the two relays ARE different). If the problem goes away then the burnoff relay is bad.

AJ123

I replaced both of the relays on the firewall behind the battery already.
I have switched the new relays no luck.

Cliff Harris

Do you have 12 volts on the MAF (pin E) when the ignition is on? That's the power for the MAF that comes from the MAF power relay.

Does the output on pin C change with engine RPM? It should range from near zero at idle to 5 volts at high RPM (and high air flow).

Do you measure 5 volts on pin C of the MAF connector when it is unplugged? That 5 volts is a reference voltage that comes from the ECM. This test checks the wiring between the MAF and the ECM.

cardo0

To fully clear the codes u need to disconnect the batt neg (i disconnect both + and - cables) then step on the brakes for 10 sec. Then u can reconnect the batt. Pulling the ECM fuse sometimes doesnt get it reset due to capacitors in the sys.

Hope this helps.

c4cruiser

What does stepping on the brake pedal do with regards to clearing codes? Especially when you state you disconnect both battery cables.

For the OP, here's the '87 FSM procedures for troubleshooting/solving a Code 36

cardo0

Try reading Automotive Diagnostic Systems by Keith McCord page 27.

AJ123

I am leaving for Beach tomorrow and won't have time to check till Sunday unless I get rained out.
Thanks Cliff

Steve

AJ123

I have been using this chart . Had the Battery out over night while replacing MAF burnoff relay . Dropped wrench inside fender wheel had to take side panel off to get to wrench.
Still 36 after running engine turning off after awhile next startup 36 again

Cliff Harris

That's one of those Internet myths that gets passed around and sounds sorta valid so it gets repeated over and over again. I have also heard to turn on the headlights. Another one I've heard many times is to leave the battery disconnected for 10 minutes, 30 minutes, etc.

You don't need to do either of these things. Just disconnect the negative battery cable for a second or so and you will be OK. For an interesting analogy that applies: how long does your computer stay on after you turn off the power?

cardo0

Are u saying the ECM doesnt have capacitors inside the circuits? How would u discharge them? It takes 10 seconds for the LED on my most of pwr supplies to extinguish - where does that power come from?

I learned this from the brake malfunction lite on my truck as the means to reset it. It was worth the 10 sec effort.

Mark8801

Cliff is right. All that needs to be done to clear codes on this old GM stuff is disconnect the battery for a few seconds. (resets the clock on the radio that fast also)


A couple weeks ago was the first time I ever heard of the "turn on a light" to drain the current myth. It sounds good but it's not needed.

AJ123

replaced relay plugs an sensor burn off replaced plug to maf sensor maf sensor replaced repaired wires with cracks. Same code still comes. Used great advice given by Cliff
will try for another week and if no luck will take it to my friends shop
hate to admit defeat

AJ123

bump

puzzigully

I have almost the exact same problem on mine.

I had a workshop work on it for a couple of days, replaced relays but no fix.

I've shipped it back to Australia and intend to work on it here.

your problem sounds like a wiring issue if your MAF didnt throw any codes on another vehicle.

I'm thinking that there may be enough of a resistance in a wire sending a signal to the ECM that it thinks it has a problem.

To me you need to confirm two things:
1. did the burn off actually happen
2. after burn off , did a signal go back to the ECM?

On the surface, this should be an easy fix, but it seems like its all too common on cars of this era.
something has to be marginal - and the wrong side of marginal..

My first step is to follow the trouble shooting guide to the letter - then measure resistances in all the relevant wires.

Good luck

Cliff Harris

Power supplies have massive capacitors in them so they're able to respond to sudden high loads. ECMs don't.

I measured the voltage on the power wire going into my ECM and disconnected the battery. The voltage went to zero in less than one second:

puzzigully

Cliff,

Awesome information right there!

Thanks for posting.

AJ123

Well this should be a simple problem to solve and it hasn't turned out to be simple. Monday into my best friends shop.

Dt86

Have you tested your "new" relays to make sure they are good? I got a bad one once.