how to test exciter wire to the alternator?

[Hinzipwo]

I have a 2001 jetta tdi alh auto and my battery light came on one day, i drove it for like an hour before it died right as i was pulling into the driveway. i swapped the alternator from my parts car and bought a new belt. put it all back together and my battery light is still on, we checked the fuse box on top of the battery and noticed a blown fuse, swapped the whole battery fuse box from my parts car onto mine, still a battery light. i'm wondering if this is the exciter wire not allowing the alternator to charge, id like to rule out the alternator as the problem as it was working fine on the parts car when it was running not to long ago. would appreciate any and all input on this. i may be looking for excuses to not buy a new alternator but i would rather try everything before resorting to that.

 

[Nero Morg]

At key on the exciter wire should see battery voltage, within 1v.

 

[Hinzipwo]

At key on the exciter wire should see battery voltage, within 1v.

right, but where do you test for the voltage, in the connector going to the alternator? its the blue wire going into the connector correct?

 

[Nero Morg]

Yes that wire.

 

[Hinzipwo]

Yes that wire.

what is the ideal ground point when testing those cables? i was using the battery post ground and couldn't get a reading

 

[Nero Morg]

Round side is T2e/1 ---- DFM < The pin reference at the 4-pin connector is T4/1

Square side is T2e/2 ---- L < The pin reference at the 4-pin connector is T4/2


The 4-pin connecctor is located at/above the starter. The other two pins are T4/3 and T4/4 which involve the AC Compressor.

My bad, it's the other wire you need. The blue wire is the signal for the cluster to control the battery light. Also, battery terminal is best ground.

 

[oilhammer]

Typically if the light comes on when the engine is NOT running, that means the control circuit is good. You probably just swapped one bad alternator for another.

 

[Hinzipwo]

Typically if the light comes on when the engine is NOT running, that means the control circuit is good. You probably just swapped one bad alternator for another.

im afraid your'e right oilhammer, i really didnt want it to come to this point but i guess ill be ordering a new bosch 90 amp unit, its 300 dollars cheaper than the valeo 120 amp

 

[oilhammer]

We put 120A Bosch in all of them, because they are less than the 90A (probably because they are more common). But that may not apply in your neck of the woods.

 

[Hinzipwo]

We put 120A Bosch in all of them, because they are less than the 90A (probably because they are more common). But that may not apply in your neck of the woods.

the part store i called only had a 90A bosch unit and a 120 valeo i would like a 120A but it seems way to expensive. might have to research.

 

[Mozambiquer]

I've got parts to rebuild yours, or I also have a new bosch in stock as well.

 

[ToxicDoc]

A reman Bosch on RockAuto is running ~$190

 

[oilhammer]

He is in Canada. I assume that is what North Bay ON (Ontario?) means? Sorry if not.

 

[Hinzipwo]

He is in Canada. I assume that is what North Bay ON (Ontario?) means? Sorry if not.

You’re correct oilhammer Ontario Canada

 

[burn_your_money]

I have a few good ones kicking around...

 

[ToxicDoc]

He is in Canada. I assume that is what North Bay ON (Ontario?) means? Sorry if not.

Well then just disregard lol

 

[Hinzipwo]

I have a few good ones kicking around...

man i wish i saw this before i ordered one from bensons

 

[burn_your_money]

Well warranty is nice to have

 

[Hinzipwo]

good news folks, the new alternator worked and my car is back on the road

 

[peteguenther]

right, but where do you test for the voltage, in the connector going to the alternator? its the blue wire going into the connector correct?

Can you tell me which connector? The one right on the alt? both wires on mine appear black - only other connector i see is above the starter and has blue brown blk/brn and grn/blk.

 

[Mozambiquer]

Can you tell me which connector? The one right on the alt? both wires on mine appear black - only other connector i see is above the starter and has blue brown blk/brn and grn/blk.

It should be the one closest to the curved part of the plug.

 

[ghohouston]

Check the 4 pin connector above the starter. Seen broken wires there before.

 

[peteguenther]

Thanks! I’ll be on it as soon ad we have daylight here.

 

[peteguenther]

sorry for the delay.. thanks for all suggestions! checked batt light by grounding the pin closest to the curved part of the alt connector and the light came on so I concluded that the alt and or regulator was bad so put in a spare that I had and it works! 14.5 V running. Not a terribly fun job though. AC compressor has to be pull aside and fan removed. Remember both the compressor and alt have those friction nuts that youlll want to tap back with the bolt in and backed out a turn to allow re-install. Also my replacement alt. had no overrun pulley clutch but seems to run just fine.

 

[Mozambiquer]

sorry for the delay.. thanks for all suggestions! checked batt light by grounding the pin closest to the curved part of the alt connector and the light came on so I concluded that the alt and or regulator was bad so put in a spare that I had and it works! 14.5 V running. Not a terribly fun job though. AC compressor has to be pull aside and fan removed. Remember both the compressor and alt have those friction nuts that youlll want to tap back with the bolt in and backed out a turn to allow re-install. Also my replacement alt. had no overrun pulley clutch but seems to run just fine.

Without the overrunning pulley, it'll put a lot more stress on the belt and alternator shaft. I'm guessing the one you put on is from a gasser? I'd recommend putting one on there.

 

[csstevej]

Not necessarily from a gasser but could have come from an automatic diesel , that what was in mine when I bought the car…..it lasted to about 350,xxx miles with no over run pulley , plus those are 90 amp alts , the manuals are 120 amp and they usually have the over run pulleys on them , I assume due to the coolant GP’s power needs.

 

[peteguenther]

It came from a manual ALH but that's not to say it was not originally from a gasser. My plan is to put a new voltage rer in the one I took out and re- install it. Can't wait- it's such a fun job! Guess I could put a clutch pulley on the one that's in there too and have a good spare.

 

[Mozambiquer]

It came from a manual ALH but that's not to say it was not originally from a gasser. My plan is to put a new voltage rer in the one I took out and re- install it. Can't wait- it's such a fun job! Guess I could put a clutch pulley on the one that's in there too and have a good spare.

Be sure to check the slip rings, they're often worn and that's what actually makes it quit charging. They should not be grooved.