[skully13]

Just picked up a 2000 SE Wagon, 2.0 L SPI with 150000 kms. Discovered that when you first start the engine, the alternator will not charge (10.80 V).

It will continue like this until you bounce the RPMs a couples times off idle, and it will start charging (13.58 V) and continue charging until it is shut off again. And then its repeat the same process to get things charging again.

Battery is good, swapped the alternator out for a known good one and same issue. Checked, cleaned, back probed all that i can think of and everything is looking normal.

Anyone else run across this issue before? Any hints before I start chasing this quirk?

 

[mikebontoft]

Well from the diagram, two wires (the blue wire and gray wire) run to the PCM..... since of course they don't tell us what those two wires function as other than "GEN" it may be an internal fault of the engine computer that's causing erratic charge

 

[FocusedSlayer]

If it was doing this before you changed out alternators you may want to start checking your grounds and make sure they are getting a good connection and also check for any loose wires at the connectors . Also you may have a bad place in a wire that is causing a grounding issue.

 

[mikebontoft]

The alternator is actually grounded through its body. If there was a ground issue on the PCM the car may not even run.

 

[VAfromMN]

I know, I know, it's a stupid thought, but is there any chance the drive belt is slipping until you goose the revs a bit?

 

[freemind]

^this.

 

[skully13]

Thanks for the replies. Definitely not a belt issue. After doing some more checks, I believe it is an issue with the PCM. Seems that the PCM is not commanding the alt charging field until it has seen a load placed on the engine. See if I can snag a PCM at the wreckers and give that a try.