Author Topic: alternator on the fritz (Read 4735 times)

dieseljt · « **on:** June 03, 2007, 08:44:28 am »

hello everyone, i am a new user and i ran a search but did not come up with anything... first off, i am new to vw diesel, i just bought a 1985 jetta turbo diesel, it is in fairly good shape other than the alternator is not charging, the previous owner must have cut the small blue and pink wires to the alt and i cant find where these hook to. from what i have found, the bosch alternator is sensitive to what it gets to excite the field windings... i had the alt rebuilt by a reputable, local shop, but i do not know where to hook the small gage blue and pink wires tom, can anyone tell me? thanks! -justin

BlackTieTD · « **Reply #1 on:** June 03, 2007, 08:48:47 am »

hey justin. welcome.

a bentley manual is a great resource when working on these cars. the manual contains detailed wiring diagrams that will answer your question.

there is also a company called 'transpo' that makes an adjustable voltage regulator for our alternators. its main function is to allow the driver to manually adjust the voltage. a secondary benefit is that the alternator no longer needs to be 'excited' to start charging. once i put one on my old car i never had to blip the throttle again to kick the alternator on. just did it on its own. they are like $25-30.

bentley for your car should be about the same on fleabay. cheers

dieseljt · « **Reply #2 on:** June 03, 2007, 10:17:53 am »

good info! thanks! i will check out bentley... but i just need to know where the pink and blue wires go as they were cut. the alt was rebuilt with all new parts, but it is not charging, i just need to get it charging so i can drive it, this is my new DD

mac.man25 · « **Reply #3 on:** June 03, 2007, 11:22:25 am »

Quote from: dieseljt

good info! thanks! i will check out bentley... but i just need to know where the pink and blue wires go as they were cut. the alt was rebuilt with all new parts, but it is not charging, i just need to get it charging so i can drive it, this is my new DD

The Blue and Pink wires? It all depends on your alternator my friend, so you either need a service manual or to check out All-DATA. In MN All-DATA is free at the local library, it includes wiring diagrams and all sorts of good stuff. Check out the local library to find out where those go.

oh, one thought, is the "pink" wire about 8-10 gauge (thicker then the other wires) and run to the starter? you connect that one to the big terminal on the alt, and the blue one, I think that's the exciter wire. That goes on one of the smaller terminals, but I don't know which or what it's called. I hope that helps.

Cullen

dieseljt · « **Reply #4 on:** June 03, 2007, 04:56:36 pm »

i think i figured it out... i know the big red wire is for the battery and goes back to the starter. i have a few shop manuals for it, but they are all vague as top the alternator wiring. i found the small blue wire goes to the warning light and provides the excitation voltage at the D+ terminal... the pink wire i am talking about i found goes to the tach (wich is also not working) and connects to the W terminal on the back of the alt. thanks for the help!