99 Dodge Dakota 3.9L
Check Engine (CE) Light & Low Fuel Light came on, gas gage stopped working, engine idles @ 2500 RPM. Code P0505 detected (IAC). Replaced IAC and TPS with no change. Replaced PCM, fixed CE and gas gage problem, but will not start. Swapped back old PCM, starts right up with all previous indicator problems back. Could this be an ASD or CPS issue?

 

99 Dodge Dakota 3.9L
CE light & fuel light came on, the gas gage stopped working and the engine idles at 2500 RPM. Code P0505 detected (IAC). Replaced IAC and TPS with no change. Replaced with used PCM which fixed CE and gas gage problem, but now it will not start. So, I swapped back with the old PCM and it starts right up, but all the previous indicator problems come back. Could this be an ASD or CPS issue? Maybe the PCM needs to be flashed?

Need HELP!

 

I will move your post to the 2nd Gen Dakota section. You should get more response there and if you don't, please let me know.

 

Where did you get the replacement PCM? I'm thinking security at the moment.

The ASD relay and the CPS both work if your truck will start with other PCM.

 

I purchased a used PCM (same part number) from EBAY for $120. After I installed it, the CE light went out and the gas gage worked. Now I just cannot get the thing started. It turns over but just will not start. I tried spraying starter fluid in the TB and it almost started for a second. I even tried more battery boost, but still nothing.

 

Check for spark, pull a plug wire and crank it.

It could be a bad PCM.

 

Would spark be an issue even though it starts right up with the old PCM? All of this started back in Sept when I would stop at a light or stop sign, the truck would die (would not hold idle). It would start up just fine and run when I kept my foot on the gas pedal. A few days later, the CE came on. So I had AutoZone check the code (P0505). I replaced the IAC and TPS. The problem went away for about 2 weeks, then the CE light came back on with the same error code, then the truck started running high idle (2500 RPM). I replaced the IAC again with no change. Then after another few weeks, the gas gage quit working and the low fuel light came on. I checked the battery (good) and checked for vaccum leaks (none that I could see/hear). From the code, it also suggested that it could be the PCM. So, hear I am, with a purchased used PCM...fixed CE and gas gage problem but no start. Do you think I may need a new PCM (not used)? Should I send the old PCM to get rebuilt? Can a used PCM be flashed?

 

Spark would be an issue if the PCM isn't triggering the coil. The PCM is the heart of the fuel injection and ignition system.

If it runs with the old PCM and won't with the Ebay, something is wrong with it. Even with security, it should start, then die.

The exchange places will program everything for you, mileage and VIN. They'll have the latest flash in it already. All you do is put it in.

 

PCM needs to be flashed with your vehicle info, VIN & mileage. It also must be an exact swap, same motor, transmission, 4wd, etc. or it will not work properly and the truck won't run. It sounds like the PCM is the issue, you just need to get it programmed if it is an exact match and you should be good to go...

 

Thank you all for the great feedback. I took it to the dealership to have the PCM troubleshot. They said that the issue IS the PCM, however, they cannot flash the used PCM I bought because it has a VIN already programmed and the security will not allow it to start. Now they are trying to sell me a new PCM and flash it with my VIN...all for $980.00!! Is there any place online or anywhere that I can get this cheaper and have my VIN programmed?????

HELP PLEASE!