LDP Solenoid Electrical Short

[lonelytoilet]

I've perused around various forums and done a ton of googling looking for any useful information, but haven't found much. For a '02 4L I6, is anyone familiar with the electrical connections for the leak detection pump and solenoid, or chasing electrical shorts? The electrical diagram that I've got, in a pdf of the service manual, isn't making a whole ton of sense to me. I'm asking because I've got two check engine codes in, p 1495 "An open or shorted condition detected in the Leak Detection Pump (LDP) solenoid circuit" and p 1682 "charging system output voltage low". I'm assuming there's a correlation between the two because my alternator is currently only maintaining my battery voltage at 12 volts. Also, in a series of short-sighted judgments, after getting these problems I replaced my alternator and battery to see if that did anything. Which it didn't. My guess is a bad, or corroded, grounding connection, but I'm not sure where to look for that. Either that or my leak detection pump solenoid is bad. In which case, does anyone know where to get one?

 

[qslim]

I think you need to focus on your charging problem. According to your diagram the LDP is spliced (S113) off of the same circuit that goes between the PCM and your alternator, so once you get your charging system working normally your LDP issue may resolve itself too.

The generator wiring diagram on page 8W-20-2 shows G104 as the ground for the generator which is where I'd check first. Not sure where it is though, the ground location index in section 8W-91 doesn't show it in a figure, it just says that it's "near the generator".

If that ground looks GTG then I'd me moving on to checking the wiring for an open or shorted condition.

What part of the diagram isn't making sense to you? We can help you decipher it.

 

[lonelytoilet]

I've taken the car to an automotive electrician and I've already gotten a call back saying that the issue is with my Power Control Module. According to them, the connections all checked out to be good, but the PCM isn't putting out the correct voltage for the alternator excitation field. Before I took it over, I had another check engine code come in before I had to make the drive up, p 0443, so I guess It's time for a new PCM? Before it totally dies on me.

 

[qslim]

I've taken the car to an automotive electrician and I've already gotten a call back saying that the issue is with my Power Control Module. According to them, the connections all checked out to be good, but the PCM isn't putting out the correct voltage for the alternator excitation field. Before I took it over, I had another check engine code come in before I had to make the drive up, p 0443, so I guess It's time for a new PCM? Before it totally dies on me.

Yeah, the voltage regulator is built into the PCM.

@Wranglerfix is the PCM guy around here, I'd give him a shout about it. I think he has a rig that can ring out the internals of the PCM or something if you send it to him.

 

[ItchyDong]

Put a multimeter on the battery posts and start it. Note the voltage while idling. Then go unplug the leak detection pump and check the voltage at the battery while running. If that LPD is shorted, it may be pulling down the voltage supplied to the alternator field winding.

This could also be checked by back probing the WT/DB (pin 1) wire on the back of the alternator while idling. Should be battery voltage present. The PCM uses an intermittent pulsed ground (pin 2) to regulate the amount of voltage to the field winding. If it’s way lower than battery voltage, something spliced into that power feed (the LPD) is probably shorted and it’s nice you have a code as a clue as to what it might be.