Thread: MAF ground?

On my 02 GT does the MAF utilize a shared ground with the other sensors or does sit have it's own dedicated ground? If it has its own, where does it ground out at? Even with a new MAF I'm getting P0102 and I'm wondering if I might have damaged it's ground point when I jacked up the motor to replace the engine mount.

It looks like it's part of two relays and has a common ground point and one wire to pcm. Here's some schematics:


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Check to make sure fuse #21 is not blown

Using these diagrams, you can run a continuity test on all the wires. But I agree, check fuse first, then proceed with checking wires.

I checked fuse 21, all good there. I did a visual inspection of the pigtail to the sensor and all looks good. My Bluetooth obd2 reader is spring the MAF is reading at 0 gm/s. I was half tempted to cut the ground wire on the pigtail and running a dedicated ground to the where the negative terminal grounds out. Any other thoughts, side from my terrible one? Ha

Test pin (and I kid you not about this, it is purely a coincidence) 69 for continuity with pin A on your MAF sensor (should be labeled). If it is open, then run a new line for that. Check for power at pin C with car running. Lastly, check pin B for correct ground. If no ground at B, run ground (shouldn't hurt anything). If it still doesn't work, it's your PCM...

Originally Posted by Scottydoggs

id try a new maf. 102 code means no power. maf could be just be shot, dont have to be a bad wire. dont get a aftermarket maf either. oem works best. im on a junk yard maf for like 6 years now. cost 40 bucks.

double check that fuse 21 is marked "ign" thats the one to check.

I'll pull the MAF and try a different one, I'll see if the local pick and pull has one. To think I sprung an extra $40 for a Dorman one instead of one of the off brand ones...

#21 is the one that's right under the IGN relay right?

Originally Posted by wstefan20

Test pin (and I kid you not about this, it is purely a coincidence) 69 for continuity with pin A on your MAF sensor (should be labeled). If it is open, then run a new line for that. Check for power at pin C with car running. Lastly, check pin B for correct ground. If no ground at B, run ground (shouldn't hurt anything). If it still doesn't work, it's your PCM...

I may be an IT guy, but I'm not that versed with underhood wiring haha. I believe you have to have a continuity tester to test continuity right? Anything I can do with a multimeter? Which pins are A, B, and C?

This should help

If resistance shows 0, there's a short

Originally Posted by wstefan20

This should help

If resistance shows 0, there's a short

Any chance you can give me a fifth grader level how to in measuring that?

Here's a website that takes you step by step through diagnostic procedures mentioned above: http://easyautodiagnostics.com/gm/3....nostic-tests-1

Alright, double checked fuse 21, no problems.

Multimeter in DC mode, red to MAF power, black to negative batt terminal, 12v

Black lead to MAF ground, red to positive batt lead, 12V.

According to the link above this post that indicates the ground and power are good. My multimeter doesn't do frequency, so I can't do test 3.

I cleared the CEL code again, it's off at the moment, but my OBD2 reader still shows 0 g/m on the MAF.

use your multimeter set to resistance (Ohms) and measure from pin 69 on pcm to pin on maf connector. If it reads OL or zero, there's a short. If it reads a small value, the wire is continuous (good). Then your options would be to either measure the frequency of maf sensor with a good multimeter, replace maf sensor, or conclude that there is a fault in the pcm and replace it

Does the pcm have a pinout display sticker and/or do you have a diagram of which one is pin 69?

FYI check engine came back on

When you remove the "cover" on the connector covering the wire harness (grey plastic cover piece), they are raised numbers cast into the connector so you can't miss them. Hopefully your wire is just shorted, or it's the maf sensor and not your pcm, although there's plenty out there so it's not the end of the world

Originally Posted by wstefan20

When you remove the "cover" on the connector covering the wire harness (grey plastic cover piece), they are raised numbers cast into the connector so you can't miss them. Hopefully your wire is just shorted, or it's the maf sensor and not your pcm, although there's plenty out there so it's not the end of the world

Do I want to test it with the car on or off?

off, and always remove the negative battery terminal before and after disconnecting the pcm. Only reconnect your battery when the pcm is connected and secured. Just a safety precaution. All you're doing in this test is seing if the wire is at fault.