Ok so this morning I drop my son off at daycare and I get back to my truck and I hit the key and it cranks and cranks and cranks. So I wait a few mins and try it again, only cranks. So I wait about 20 mins and then it starts up YAY!!! I look down and DAMNIT check enigne light is on... So I drive it home and hook the scanner up and read the code... Shows a P1389 ASD Relay Voltage. Now the truck starts up fine and runs fine... Anyone have this problem before?

 

Next time it does that trick, swap the asd relay for the wiper relay, and see if that doesn't fix it. (relays are in the PDC, black box behind the battery, under the hood.)

 

I currently have the same problem. To complicate things, my PCM has FRIED! I have installed another PCM and it is getting hot as well. Melting down around pin 12 on connector C3 which is the pin that is being monitored for the ASD relay output voltage of +12 volts. The ASD relay is working as I have swapped it out and it made no difference. I have +12volts on pin 87 of the relay with key in RUN position for about 2 seconds then it drops out as it should. (PCM turns off the ASD relay when key is on and no pulses are seen from the cam position sensor.) When the key is moved to START position, the ASD relay picks again and while the starter cranks the engine I am getting about +9volts on pin 87 but engine will not start! DTC code 1389 in the PCM when checked with scanner.

2001 RAM 1500 5.2L AUTOMATIC 4x4

Checked fuel at fuel rail = GOOD
Checked for spark at plugs = GOOD

WHY IS MY PCM BURNING UP around the pin on the C3 connector?

 

Cmon guys....somebody take a stab at it!

Called a few of the PCM rebuilders to try to obtain a diagram of PCM internal circuitry but none of them could supply one or assist with any troubleshooting. I know its not the PCM but without some knowledge of what is going on inside it is difficult to say why it would meltdown like it has. Does anyone know where I can get some insight as to what the PCM insides might look like?

 

P1389 No ASD Relay Output Voltage at PCM

PCM isn't seeing the voltage. Better have a look at that connector again. No clue why it would get hot enough to melt things, unless you have a short in the connector itself.

 

After burning two PCM's, I can tell you that the key to understanding the ASD circuit is found in the factory tech manual:


generator current output accordingly.

I found the short in the wiring harness after many hours of troubleshooting.
Putting the voltage regulator circuit inside the PCM seems to make the PCM the weakest link in the extensive ASD +12V circuit which is used all over the truck! The entire circuit is protected by one 20 amp fuse which did not blow but let the PCM fry instead!
What kind of engineering is that?

 

The P1389 code was also quite misleading as it really was a symptom of the PCM burning itself up rather than the cause of the problem. There were also other symptoms such as ammeter dipping towards 6 volts and A/C compressor kicking on when dash selector switch was set to OFF! All related to the PCM frying itself.

Oh well....all is working well now.

 

Just thought that I would mention that the replacement PCM came from a local junkyard. It seems to be working flawlessly. The one I ordered from ALLCOMPUTERRESOURCES.COM had problems that they could not resolve even after two replacement cycles. They say that there must be a problem somewhere in the vehicle! So I am out $225 for that boat anchor! But I am happy that my truck seems fine now.

 

I am having the same problem. I havent found the issue that keeps blowing the new pcm's. i.e. 2 already. but i did wire in a 3amp changeable fuse in the green orange wire at the connector 3 pin 12. a.it only blows the 3amp fuse and it hasnt blown the new pcm. i did this because i have 600 dollars of burnt pcm. i cant find the short yet but it allows me to drive my truck every day and it saves my new pcm. i have been leaving my truck full of gas for the last week. i mean i dont even let the needle move off full. becuase i have a strange idea that the leak detetion pump it is shorting out. any ideas... but the 3 amp fuse is a money saver and keeps the truck moving.

 

I am having the same problem. I'm on my second pcm. It ran for about an hour just idling in the yard, and both pcm's fried after about driving 10 miles. After that fuel pump runs all the time. If I spray starting fluid in air cleaner it fires, but not when cranking. Mechanic had it for 2 weeks couldn't find a short. He said it was computer. I'll try the inline fuse on ASD feed. How many fuses do you blow. does it let you drive very far?