Solved 2000 Explorer P0102 and P0113 codes

[Montana Daze]

Hello again guys

Somehow I knew this wasn't over

The salvage engine is running quite well with a couple exceptions, it's giving me P0102 and P0113 codes. I installed a new MAF/IAT sensor as a matter of course when I put the other engine in and the codes came up on the first driving cycle. I cleared the codes and drove it again,; the codes came back. I disconnected the battery and let it sit for a few hours, drove it and the codes came back. I checked and the plug is all the way in and secure in the new sensor.

Live data sez IAT is -40 and MAF is 0.19 lb./min. When cold, testing indicates I have power in the circuit and both grounds are working. When up to operating temperature, MAF signal is .079 volts @850 RPM and 1.8 volts @2000 RPM however the check engine light stays on and the live data does not change with increase of engine speed. A -40 IAT reading is hard to believe on a 80 degree day.

I don't think the signals are getting to the PCM. That being said, what's the most likely cause, a broken wire, a bad pin in the plug or PCM, or something I've not thought of?

Regards,
Mark

 

[C420sailor]

Those values are out to lunch. IAT should be ambient or greater. It isn’t uncommon to see 140-160° on a hot day in traffic. It gets hot under the hood.

MAF at idle should be closer to 0.7-0.8ish, from my memory. 0.19 is way way too low.

Disconnect the PCM and IAT/MAF and start checking for continuity/resistance. You’ll need a PCM pinout diagram.

Also clean the grounds, esp the PCM ground next to the connector.

 

[Montana Daze]

Thanks 402S for the response and advice

About to start this; I'll clean the plugs with NAPA/CRC QD electronic cleaner aerosol and start testing. I assume the pin in the PCM plug for the MAF (#36) will have D terminal on the MAF/IAT plug as it's other end.

Is it a good idea to use silicone dielectric grease on the PCM plug?

 

[Montana Daze]

Did what I could...checked plugs, all connector pins straight and even. The female side of the plugs appears in good shape, all at the same depth in the plastic, bright and shiny. Cleaned all the grounds and attempted a continuity test of the harness between the MAF/AIT and the 104 pin plug that did not go well; all I got was open loop on the meter. I have no idea why, it don't seem that the thing would run at all if this were so. I did find a pinout diagram here on this site so I'm pretty sure I've got the right ends I'm trying to test.

Another driving cycle brought back the same codes along with the same live data readings on the scanner. This is beginning to get infuriating

 

[Montana Daze]

OK so for today's adventure I was able to obtain very thin meter probes, and it occured to me that I happen to have a spare engine harness lying about. Much easier to map it out on the bench than bent over under the hood.

Sometimes I am dense

I already know that on the sensor plug that terminals A, B, and C are working as they should so they are of no concern to me. The latter three I traced out and my findings are thus:

Terminal D goes to pin 88, MAF input
Terminal E goes to pin 91, IAT signal return
Terminal F goes to pin 39, IAT input

This tells me that I should be looking for continuity on D to 88, E to 91, and presence of current on F to 39. The pin diagram posted by Dogfriend 15 years ago was helpful thanks it yer still around. I'll start tracing next but it's over 100 in the garage now; I'll wait 'till it cools off some.

It's possible, I guess, that there's a portion of the PCM that's gone bad.

 

[C420sailor]

Could be. Wouldn’t be the first time.

But if you didn’t have this problem before, and this is a ‘new’ harness...

Beauty of this problem is the simplicity. It’s either the sensor (which you already changed), the harness, or the PCM.

THe fact that both the MAF AND IAT portions of the sensor are inop tell me that something in common between the two is at fault. Do they have a common ground? Common reference voltage/power wire? Some commonality on the PCM board? I don’t have a schematic in front of me.

Edit: you’re clearly a good wrench, considering the work you’ve done. You’ll figure it out.

 

[Montana Daze]

I'd have to agree, simple problems are much better.

Took the morning off and shot prairie dogs it was good to get away from this for a time

This afternoon I was back at it. Continuity testing resulted in open loops on MAF input, IAT input, and IAT signal return wires so it appears the culprit has been revealed. Now I have to decide if I'm gonna remove the upper and lower intake again to trace down bad spots in the wires or just cut them off at the plugs and run new stuff. The former plan lacks appeal, the latter backyard approach is much more to my liking altho I'm not sure it's best practice...at this point as long as it works I really don't care. Any thoughts?

Regards,
Mark

 

[C420sailor]

I don’t have a schematic or my truck in front of me...but do those wires run through the other major connector in the engine bay?

It seems weird to me that, of all the wires in the harness, only the MAF/IAT ones are open. Which makes me think it’s unlikely to be buried deep in the harness, and instead closer to the sensor.

I’d backprobe and see if you can figure out roughly where it is in the harness. If it’s in a ***** of a spot, then I’d consider just running new wire and calling it a day.

 

[donalds]

All the power wires and ground wires for the engine sensors and injection components

Here's a pic
I suggest you take a look for a bad broke wire where they're tapped together

 

[Montana Daze]

420 I'd not thought of that, it's an excellent idea as it sure would make my day if it turns out to be a bad plug. On these everything runs down the big bundle in between the heads under the intake manifold and as can be seen from Donalds pictures it's a giant mess. I also very badly don't want to take the intake off again I am tired of it. I don't think anyone has a schematic of one of these I've looked high and low for one with no success. Even the Ford dealers which I called four of don't seem to have them outside of the very expensive shop manual and what you get in the Haynes manual is a bad joke.

This train of thought does make sense as the affected terminals D, E, and F are on the outside of the plug on the sensor end. I envision it thus: Gorilla works on his exploder...Yanks sensor plug by the wires...Predictable results. In retrospect I probably should have used the harness off the old engine which was a known quantity.

I'm actually getting kind of cranked up with the end of this potentially in sight. Thanks for the responses and ideas I'll let y'all know how it turns out

Regards,
Mark

 

[Montana Daze]

As it turns out pin 91 to plug had continuity, my error as I was incorrectly looking at how the plug oriented going into the PCM...I was visualizing it upside down.

Cool, only 2 wires. The plug is kind of a chore to get to and identify wires, here I've done that and marked those I'm looking for with black tape

Decided to go the Cletus route (after all that's me) and run new wire

and alltho it looks awful it works. Just lit it off five minutes ago and my scanner sez IAT is 82 degrees. I don't remember what the MAF is pulling, perhaps 0.85 lb/min and it shows a corresponding increase when RPM goes up. I think it's fixed.

I'm rather tickled especially since I managed to not yank anything else loose on the PCM plug while manipulating it, and now time for another driving cycle to see if it lasts.

As always thanks much for the responses and advice offered, it helps when others bounce ideas off me since it gets me to think more clearly

Regards,
Mark

 

[C420sailor]

Good job! Those numbers are solid. Loom, tape, and zip tie those wires and she’ll be ready to rock.

 

[Montana Daze]

Thank you sir

I've always liked the older vehicles, I'd have pre-electronic ones were it not for the problems of gas and parts for them.

There's a certain satistfaction in keeping one of these relics alive