'85 Targa D+ blue wire on alternator

[Hoegenauer]

OK...alternator not charging. No indicator light when key on.

I pulled the D+ blue wire from alternator per book and grounded....still no indicator light on dash. From the same ground I went to bulb terminal at Blue/red and bulb lights brightly (bulb definitely good).

There appears to be a break in the blue D+ wire from the alternator to the blue/red on the bulb terminal. Continuity test is negative.

The wiring diagram shows direct path. but for the wire to change colors, there is a connector somewhere. Anyone know how this is routed and where the connector might be?

Thanks as always.

[JWLindsey]

You might check the diode that is in line with bulb. If you pull out the gauge from the dash there is a plastic connector in the wire that runs from the bulb. The diode is in this connector and prevents potential backflow from the alternator through the D+ that would keep the car running after you turn off the key. Mine was scorched after a voltage regulator spike and I had the exact same symptoms. If it is the diode, you just need to bop down to an old school auto electric shop to pick one up (think it is a 12V/1.5W job) and then figure out a way to solder it into the circuit. I just cut up the old diode and used the metal terminals in it to make up a new connector. Looks like crap but works great.

Good luck!

-JWL

[Hoegenauer]

I don't see a diode, but on further research, the wiring is more like the 86. Maybe an '85 mid year change? I had a similar issue buying other parts for my '85 (I needed '86 parts)

The blue/red to the bulb is from the factory alarm module and I have continuity to the bulb socket...so it is in the blue D+ from the battery that I seem to have issues with. There is a a blue to the alarm module, but not continuity with the D+.

Does anyone know the routing of this blue wire to the alarm module. I really do not want to tear up a relatively clean harness trying to chase it. Does it go through specific connectors in the engine compartment or the trunk? At least that way I could isolate a portion of the harness.

[Hoegenauer]

For the sake of helping others in the future...the blue D+ wire off alternator goes to multi-pin "block" connector in engine compartment fuse box. The connector is behind the aluminum plate that mounts the fuse holders. You do not see this connector until you slide the wire bundle towards front of car and then you can unplug and inspect. Similar to other connectors in the car, the pins can be inspected by prying off the top of the plug half of the connector. From there the blue D+ it travels drivers side in main wire bundle to the front trunck space and accross to the alarm module with no other apparant connectors.

As for my issue...there is a break in the wire from alternator to connector and moving the bundle around made continuity. I will probably run a new wire outside parrallel to the bundle so I dont have to cut intact factory sheathing around wires and splice in at connector.

I have a light on dash...now put it all together and hope I am charging.