Hello.

I am new to this forum. I have been a member of the Fiero Forum for a long time. Just finished rebuilding an '88 GT and all I need is to finish the brakes and it will be back on the road.

I have a 2001 Dodge Dakota with only 63,000 original miles on it. I have rebuilt the whole front end, as it was a mess. Shortly thereafter, the ECM went south. The transmission went to "Limp-in" mode and got me home. I thought it might the be solenoid pack in the 42E tranny, but when I pulled the pan, there was a big chunk of an internal snap ring on the magnet in the bottom of the pan. So I took the truck in to have the transmission totally redone. After It was done, on the second day of use, the truck went back to limp in mode. Did some checking and found the voltages coming from the ECM were wrong. The truck sat for a while while the transmission people were trying to locate an ECM. They were going to handle it under the warranty, as they didn't catch this when they did the rest of the tranny. Do to COVID and supply chain issues, after three months of the trucking sitting at their garage, I took things into my own hands and located a rebuilt ECM with a warranty and paid for it out of pocket. I installed it and things were fine for about 2 days. Then the check engine light came on. I read the codes. P0141 and P0161, pre CAT and post CAT O2 sensors.

I am just wondering why both of them would be bad? Could the truck sitting for 3 months have anything to do with it? Maybe a wiring issue, since the pre CAT sensor is close to the tranny? Any suggestions would be appreciated. Thanks in advance.

 

Those are for the O2 sensor heater circuit. I think there is a relay in the PDC that supplies power on that circuit, likely a fuse as well. Have a look, see what you find.

Welcome to DF! Moving this to 2nd Gen Dak section for ya.

 

Thanks. I noticed the different classifications after I had posted this. Sorry. I will look and see. I assume this will be in the fuse box, right? Is PDC an acronym for power distribution center, namely the fuse box? I thought that it would be kind of strange for both sensors to fail at the same time. This is why I asked. If they are both fed from the same circuit then it would make sense if a fuse blew. The transmission people may have had something to do with this, since the wiring and connectors appear to be in the transmission area. Thanks again for the info. I know a lot about cars in general and electrical stuff in particular, since I worked in Prime Power for around 40 years before retiring. I love re-doing vehicles and putting them back on the road.

 

Yeah, fuse box under the hood.

I think one of the harnesses for an O2 sensor or 2 go up over the trans, and are clipped in place right on top of it. (and there is a connector there, stupid design so far as I am concerned, almost impossible to reach to unplug the O2 sensor.) They might have pinched a wire.

 

Thanks. I will check it out when it quits raining here in CA. We've gotten close to 3 inches since late afternoon and it's still pouring. We'll take it though!! We've been in severe drought for a long time.
You're right, though. I looked at the routing of the wiring and it appears that they could have done a much better job!! There is a lot of room under the truck. Why did they have to jam it all together there?
Later...

 

I found the problem. I figured before I got under the truck, I would try the easy stuff first. I found the O2 sensor relay in the PDC. I pulled it and tested the resistance of the coil with a Fluke 87. It read open. As a doublecheck, I connected it to the battery with a couple of test leads. I did not hear the relay operate, and measured the normally open and normally closed set of contacts in the relay, just to make sure. No change of state. Went to the local dealer in town and they had one for $19. I popped in the new one, cleared the codes and have been running around all day in the truck with no codes popping up. Thanks so much for the help, Hey You !!!!!!!! You saved me a helluva lot of time.

 

Excellent.