1

My truck had been throwing intermittent MAF codes for a month, P0102 "low or no voltage." I only noticed due to the rough idle and "stumbling" on acceleration. I finally got around to giving the MAF a cleaning hoping to avoid replacement. I used proper MAF cleaner and even disconnected the battery first out of an abundance of caution. Let it dry a full hour before reinstalling too.

There was no sign of stumbling, no MAF codes and truck drove well but I soon noticed the coolant temp gauge was stuck at the bottom of it's range. I routinely check my gauges on every drive and know it was working before I cleaned the MAF. Now it was showing code P0116 for low/no/out of range voltage for the coolant sensor. Hmm.

This was the first time in the year I've had the truck that the coolant gauge malfunctioned and it seemed very coincidental that it started immediately after jostling the MAF sensor wires cleaning that sensor. Now, a few days later the temp gauge has started working again and simultaneously the MAF sypmotoms are back and as bad as ever. Like a matched pair one goes away and the other appears.

I had my truck in for inspection during this same time and my mechanic said both the coolant sensor and gauge were good and that the BCM is likely at fault since the PCM is seeing the temp reading wether the gauge works or not. But I just don't think the timing of events is just coincidence.

As far as I know there's no circuit connections linking the MAF and coolant sensors but what about the possibility that moving the MAF wires shifted a loose connection into place in them while opening a gap in the wiring for the coolant gauge? Given that a few days have passed all the wires could have settled back into their original resting positions with matching behavior.

I know the previous owner had done a lot to the wiring harness but have no idea what. So is there any merit to the idea that either or both sensor issues could simply be linked gremlins in the wiring? The only thing worse than needing a new MAF AND BCM is getting them only to find they don't fix the issues.

Thanks for your time.

Improve this question
1
  • If the previous owner did "modifications" to the wiring harness, I'd definitely start there for diagnostics. Unfortunately, finding electrical gremlins is probably the hardest job (time consuming) to do in any vehicle diagnostic check. I think there's probably a lot you need to verify before going to new MAF and BCM. If you know of someone with the same MAF, you can easily swap it out to see if the problem remains or is cured. The BCM on the other hand isn't as easily diagnosed. It controls a lot and different things. Anyway, not an answer, just some random comments.
    – Pᴀᴜʟsᴛᴇʀ2 ♦
    Commented Sep 14, 2019 at 12:23

1 Answer 1

Reset to default
1

That's usually a break in the wiring harness to the MAF sensor. Pretty common actually. Disconnect electrical connector to MAF. Key in RUN position. Check for battery voltage on Pink wire. If you see that, flex the wiring harness to see if it stays. Check for good ground on black wire. Flex harness. If you find intermittent, fix the broken wire.

Improve this answer
1
  • Thanks for the feedback but it seems the previous owner replaced all 5 MAF wires with the same color. Smh. Any idea how to figure out which is which without frying anything? I mean all five wires are white now so while the 12v hot should be easy to figure I can't exactly just go by "pink" etc. So how can I tell the other four apart without damaging anything?
    – John LA
    Commented Sep 18, 2019 at 22:24

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .