Another PCM problem

[GD]

I had a problem similar to GHarman's. I would have strange things happen depending on the temperature. When I first started the truck the battery would not charge, the AC would not work and it would not go into overdrive. After the engine compartment got warm then everything would work. Sometimes my 'wait to start and water in fuel' light would blink. I verified it was the PCM by using a hair dryer in the morning to heat the PCM. I found a few companies on the internet that would rebuild the PCM. I ended up sending it to AutoTech Microsystems. When I got it back everything worked for about 10 days. Now the battery won't charge after the engine compartment gets warm. I get a 'Check Engine' light and a 12 and 42 code when I do the on-off-on-off-on thing to retrieve the codes. The 42 says that there is a problem in the charging circuit. My manual doesn't give a problem for the 12 code. Does anybody know what a 12 code indicates?

I am going to call AutoTech to see about sending it back to them to fix. I am also thinking about not using it at all and just wiring the manifold heaters to a switch. I have an automatic transmission so I would have to wire a switch for the overdrive. I always wondered if I do that could I switch it into overdrive before it gets to third gear or is there something mechanical in the transmission that won't let it go into overdrive while it's in first or second gear? I just got back from a 200+ mile trip and it would have been a long drive if it wouldn't have gone into overdrive.

Even if AutoTech gets it fixed for me I think I may put some bypass switches into some of the circuits so if the PCM goes out on me I'll still be able to drive it normally.



Anyway does anybody know what a 12 code is and can the transmission be put into overdrive before it gets to third gear?

Thanks.



GD

 

[Philip]

The 12 code is start of test. There should be one other code for end of test. I think it is 55.

 

[mysteryman]

I believe code 12 means the crank is not turning. code 55 means test has completed/finished

 

[dpuckett]

To add to mysteryman's comment- check the gap of your crank sensor. It should be . 050" +/- . 010"



DP

 

[GD]

I just rechecked the error codes. The first one is 12 and the second one is 41. 12 is not listed in the factory shop manual I have. 41 says there is a problem in the alternator field circuit. I put 12 volts across the 2 alternator field terminals while the engine was running but there was still no charge current. I measured the resistance across the field terminals and it was about 71,000 ohms. I would have expected it to be around 10 ohms. I guess I will take the alternator someplace to be tested. The 12 code puzzles me. I'm not sure why it's not listed in my shop manual.



GD

 

[GHarman]

PCM source

Just wanted to let you know that NAPA does carry the PCM for the AUTO TRANSMISSION Model 1st Generation Dodge w/5. 9 Cummins.

I need to check my crank sensor also and make sure it is gapped properly and need to learn the PCM Code retrieval method. GregH

 

[cerberusiam]

I just rechecked the error codes. The first one is 12 and the second one is 41. 12 is not listed in the factory shop manual I have. 41 says there is a problem in the alternator field circuit. I put 12 volts across the 2 alternator field terminals while the engine was running but there was still no charge current. I measured the resistance across the field terminals and it was about 71,000 ohms. I would have expected it to be around 10 ohms. I guess I will take the alternator someplace to be tested. The 12 code puzzles me. I'm not sure why it's not listed in my shop manual.



GD

The 12 means PAY ATTENTION starting to list codes. When you hit a 55 that means it is done. 12 is the test code sequence startup indicator.

 

[GD]

Thanks everyone for the replies. I pretty much determined it's the alternernator that went bad. I'll have to remove it this weekend and take it somewhere to be tested.



GD

 

[Kirwin]

12 code is battery disconnect

The 12 code means that the battery has been disconnected (IE PCM lost battery power) in the last 50 key on cycles. There is no start of test code only 55 which means end of test will come up if there are no codes. Ken Irwin

 

[GD]

The 12 code must be from when I put in the new PCM. Thats when the battery was disconnected. I can't believe the alternator went bad just two weeks after I replaced the PCM. I replaced the alternator this last weekend and all seems okay. Is there a way to reset the PCM so there are no error codes or do I have to wait until there have been 50 start cycles?



GD

 

[Kirwin]

You can't get rid of it as far as I know

It will stay present until you hit 50 key on cycles. Its just not worth deleteing it. As long as you know what it is just ignore it. Ken Irwin