Hello,
I need help troubleshooting my newly purchased 1991 Dakota with a 5.2. The truck did not pass Ohio E-check When I purchased the truck I could not see the check engine light because when I removed the dash I found tape covering the light. I removed the tape and was able to retrieve the codes. I have 12, 41, 51 & 55 as the codes. Here's the E-check readings if that helps, HC (hydrocarbons) 482.3 with a 137.0 Limit & CO (carbon monoxide) 10.45 with a 1.52 limit. NO & CO2 Passes.

So far I tuned up the truck, plugs, wires, cap, rotor, PVC, fuel filter and air filter.

Please help.
Thanks,
Russ

 

12* Direct battery input to PCM was disconnected within the last 50 key-on cycles (normal)
41** Generator field not switching properly
51** Fuel system lean
55* End of error messages (If you get this only, no errors were found)

https://dodgeforum.com/forum/1st-gen...-96-codes.html

 

Thanks, for the link.

Now I'm looking for advice on how to fix code 41. I was able to troubleshoot the 51 code and replaced the o2 sensor. So far code 51 is gone. Just a note on code 51. The engine was running rich and only getting 10 mpg, not lean as the code indicated. The spark plugs and exhaust are very black as a rich condition. That's what lead me to replace the o2 sensor.
Code 41 I'm not having any luck fixing. I've checked the charging system and it's charging fine. Something I think is odd is when I removed the battery cable to reset the ECM I get code 41 without even starting the truck. I think the voltage back to the ECM is missing/low or the ECM is bad. I've inspected the wires and nothing looks bad. I would like to know which wire at the ECM is from the battery/alternator.
Does anyone have a wiring dig. of the ECM for a 1991 Dakota with a 5.2? I don't want to replace the ECM unless I'm certain it's bad.

Looking for help.
Thanks.