Drove home from work today. Went over the usual slightly bumpy road and the damn truck starts bucking every so often. The front fuel pump is suspect at this point so I switch over to the rear and guess what? It still bucks and loses power randomly. Pull over to let traffic go and I just take it easy the rest of the way. Once I get home I decide to check codes for the hell of it. KOEO pass, 111. When I get to continuous memory I get 212 and 628. I looked up 212 and it is described as a loss of IDM input to the PCM. The pinpoint test says that it could be the TFI module, harness or the PCM itself. The TFI module was replaced ~4 years ago. Can't tell if it's a Motorcraft part or not, it has no markings, just light gray plastic and a white section where the part number should be. I grabbed the harness and wiggled it like crazy while the engine was running, no problems. Wiggled the PCM harness, no problems. So ... order a new TFI module or crack open my PCM?

 

Bump. Any ideas?

 

Code 212: Loss of IDM input to EEC or SPOUT circuit grounded.


The IDM signal is derived from a 22K ohm resistor from the coil to the computer.


So it could be a simple resistor issue or as noted in the code definition the SPOUT circuit could be grounded.

 

Aftermarket reverse engineered. Ford part has Mototrcraft prominent.

First thing I'd change.

 

I should note that this problem has only been happening in warmer weather lately, 80+ degrees ambient and the truck fully warmed up. I can drive to work no problem every morning.

 

Update: have not had a chance to actually check the wiring ... Cleared the codes and drove to lunch and back. Truck runs normally, no loss of tach signal or power. Checked codes again and it's STILL throwing 212. No symptoms showing yet but I will check wiring tomorrow. Rla where is the 22K resistor physically located in the harness?

 

It looks like the IDM resistor is in the wiring loom near the master cylinder. Found this post: Code 212 help needed - Ford Bronco Forum

It has a photo


May be in a different location for a 1991, but should be close.

 

Thanks a bunch! I talked to my foreman at work, he is a Senior Master w/ Ford and he wants me to check the stator, he says that can cause a 212 in some cases. If it's black it's the original?

 

Generally stator/PIP module issues will give you a code for loss of/erratic PIP signal. But not always.

Failing TFI modules typically act up when they get hot, so it doesn't surprise me it coincides with warmer weather.

 

Yeah I've heard that's usually the case with these TFI modules ... It's just so random though, seems like it wants to die out of nowhere. It only lasts a split second and regains power. The consensus of my coworkers is that if a TFI module is bad, it usually doesn't wake up - when they die, they stay dead.

 

Not really. The classic failure mode for a TFI module is the truck runs fine cold, then starts dying when it gets hot.

 

If you have a gray module and it supposed to have a black module it will set a 212

 

Pretty sure 1994 up that use the black ones. My truck used the gray one.

 

PIP signal is monitored on Pin 56 of the computer. Pin 4 is IDM. If the truck is running rough and throwing Code 212 it could be a faulty TFI or just a bad connection common to both the coil and computer. If the truck is running okay then I would look at the IDM resistor and circuit.

 

Checking wiring presently, will report with numbers ...
Edit: Checked between the coil connector and pin 4 of the PCM with it all unplugged and got 21.5K ohms, they want at least 22K ohms. Wiggled the harness and BOOM it goes OL on my meter. That wire must be damaged?