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My dad's 2000 xlt 4x4 will not start anymore. He left the plug on the hpop off accidentally when he started the truck and noticed a lot of smoke from the tailpipe and saw that oil had splashed all over the engine. So he cleaned in up filled the reservoir back with oil and now it doesnt start and the truck keeps blowing the PCM Power diode and unlike everyone else that seems to have this problem the #30 fuse is perfectly fine and we even switched around the idm and pcm relay. Now the truck did have a code for PCM KAM error before this happened to tge truck and we noticed it had a 15amp fuse instead of a 5amp for the KAM memory. Checked engine for shorts as well and only found the ipr wires bare, they could have touched and also I believe the gpr is bad as well. Unplugged fuel heater also. ONLY THE DIODE BLOWS, is that gonna be a bad or shorted out pcm? Did the ipr shorting out fry the pcm? Please help!
That was a mistake you wont make twice, the only reason to remove that plug is to work on your HPOP, changing the lines, or replacing the pump, it gets it's oil from the crankcase, the engine oil pump. No you didn't damage anything from the ICP, but you do need to buy a new plug end and replace it. The diode is nothing more than a one way check valve, it allows current to flow one way, I have gotten water in my PCM due to a leak in my windshield, blew dryed it out and I was back on the road. You had an ugly oily mess, one quick test completely unplug the alternator all the wires replace the diode and see what happens. I am sure by now you stocked up on diodes right? Something is back feeding when it shouldn't be. Since you washed with fresh water I would not sweat it too much, It's just the matter of finding it. Did you clean the engine good enough??? Engine degreaser? did you buy a case? You have to get all that oil off of the engine, FICM,PCM connectors, fuse box/relay box, intake manifold, plugs into the valve covers, every electrical connection needs to be clean, just wet with clean water than we can go from there.
We bought the truck a year ago and it can spin the tires with gas and a light braking, so im assuming it is tuned but dont know with what tune?? Im guessing at least a 100hp tune.
That was a mistake you wont make twice, the only reason to remove that plug is to work on your HPOP, changing the lines, or replacing the pump, it gets it's oil from the crankcase, the engine oil pump. No you didn't damage anything from the ICP, but you do need to buy a new plug end and replace it. The diode is nothing more than a one way check valve, it allows current to flow one way, I have gotten water in my PCM due to a leak in my windshield, blew dryed it out and I was back on the road. You had an ugly oily mess, one quick test completely unplug the alternator all the wires replace the diode and see what happens. I am sure by now you stocked up on diodes right? Something is back feeding when it shouldn't be. Since you washed with fresh water I would not sweat it too much, It's just the matter of finding it. Did you clean the engine good enough??? Engine degreaser? did you buy a case? You have to get all that oil off of the engine, FICM,PCM connectors, fuse box/relay box, intake manifold, plugs into the valve covers, every electrical connection needs to be clean, just wet with clean water than we can go from there.
Engine is pretty clean, we have 2 diodes left thats all that was in stock and yes some degreaser. Does the diode blow from backfeeding? Because the #30 fuse is fine. I will double check to make sure everything is clean and tidy.
Exactly it's like a backfeed, they allow voltage to go only one way, you should have another in there for your a/c compressor, because once that closes it's basically a generator and they dont want it to screw with the sensative electronics, like the radio, power everything and without the diode you could not shut it off, it would make it's own electric field, hence diode. PCM could be wet, it's easy to dry out, you have to make sure every plug is dry, clean and a dap of dielectric grease. Pain in the ***, I know but I didn't leave the plug out did I.
Exactly it's like a backfeed, they allow voltage to go only one way, you should have another in there for your a/c compressor, because once that closes it's basically a generator and they dont want it to screw with the sensative electronics, like the radio, power everything and without the diode you could not shut it off, it would make it's own electric field, hence diode. PCM could be wet, it's easy to dry out, you have to make sure every plug is dry, clean and a dap of dielectric grease. Pain in the ***, I know but I didn't leave the plug out did I.
Pcm could have gotten wet but I dont think it would have from this incident, my dad cleaned the truck with a rag first and thats when the diode went out and then washed the engine and dried it and still blew the diode. Do you mean the idm could have gotten water since its outside the truck? And is it hard to get the pcm out?
The pcm is real easy to get out, just to let you know, the harness's plug in through the firewall, but if it started happening when your dad wiped it down with a rag, retrace his steps and work in those area's.
There are three possibilities which cause the PCM Diode to blow.
* Check the harness under the Fuse Distribution Panel for a short. Wiggle it good before continuing.
First is the charging circuit. Disconnect the Alternator B+ Post and 3 Pin connector and try again. If the truck remains running you've identified the failure.
Second is the PCM. You will need to bench test it to determine if its operational.
The other, not so simple:
Somewhere in the 104 Pin wiring (or inside the PCM Circuit Board, there is a (+) touching a (-). Any time (+) contacts (-) the (- Bios) Diode burns through.
If the above does not prevent it from blowing, to tackle this is to remove the 104 Pin Connector from the PCM.
Get a PCM printout (attached) and use an OHM Meter and test across circuits for PCM (+) and (-) until you find the two that has continuity across (+), that will be the individual circuit with the problem. It can be anywhere from the PCM to the sensor. Most sensors use a common ground from the PCM so that makes it even easier.
Then, trace the wires to see where the chafe or melted cross short is.
