1986 Golf 1.6 N/A Crank No Start

[jhax]

yes sir, that is that blue alternator wire i was talking about

[scrounger]

I don't have my schematic in front of me but I think the light goes out when there is 12v on both sides of the bulb (LED).  If there isn't 12v going back into it there is no charge.

[TylerDurden]

Ja, that's how it works.

The bad ground is a likely culprit. Had it happen myself ( a dealership car actually) and heard many others too. I'd ensure the ground cable is cleanly connected at the engine/tranny, chassis and battery.

[8v-of-fury]

Which should always be checked prior to winter as preventative maintenance

[jhax]

I just look at the schematic, looks like the blue wire hits a resistor and then to the LED, comes out and hits a common wire (connected to many other LEDs) and comes out as a YEL/RED wire going to fuse 21. So if i check that YEL/RED wire at the back of the plug coming out of the instrument cluster it should read 12V.

I replaced the negative batter cable tonight, just waiting for the battery to charge.

[jhax]

8-V, i live in tempe az, there is no winter here. It was 55 today.

[scrounger]

The resistor is used to limit the current to the LED.
I bet if you put a switched battery voltage on the blue wire you will have completed the circuit. and get alternator output.  Of course you will loose your battery charge light. The resistor probably drops 8 or 9 volts. Most LEDs run at 3 volts.

[TylerDurden]

Agree.

AIUI, the alt get's its initial field excitation from the 12v via the LED. After the alt develops current, it self-excites. If there is no 12V at the blue wire, the path or led is open. The field bypass above can temporarily provide initial excitation.

However...

 If there is 12V at the blue wire when connected to the alt, but the alt output is low, a failing ground path from the alt to battery can keep the field coils from pulling enough current to excite, or drop the output voltage.

A jumper cable from alternator bracket to battery (-) can bypass bad ground (as a diagnostic).

[8v-of-fury]

A jumper cable from alternator bracket to battery (-) can bypass bad ground (as a diagnostic).

I put one on anyway for safe measure. You can't have a good + and a crappy - and expect anything to work at any higher amperage.

Stereo guys often put the 0/0 gauge power wires from the battery to their amps, and then run a 10 gauge ground wire to the sheet metal in the trunk.. relying on all that power to go through the stock body-battery ground. Big positive, Big ground.

jhax - I wouldn't know that because your profile does not state where you are located Update it at your earliest convenience please. I just assumed as usually "no start" threads at this time of year are from cold climates.

[jhax]

Sorry, 8-V i changed it. So from what I understand, run the alt excite wire straight to a switched 12v in the fusebox? I charged the battery tonight, I need to work at 5:30am so Im going to conserve the battery for tonight and check again tomorrow. Thanks for all of the advice guys. I appreciate it, i wish I had the $10k i need to just get the tdi in already. anyone want to donate to the Justin's TDI Build Fund? 

[air-cooled or diesel]

personally i like to run a few grounds. ground goes from neg- to trans/motor, another ground (2) from neg- to body, i like to run grounds from trans/motor to alt bracket, from alt bracket to (large) fuel filter mount studs, you can also run another from stock points trans to body, and another medium ground from neg- to another good body point. clean all contact points and you can even seal as a last step(outside engine bay). use at least 1 washer on all connections.
when doing this becareful of new found shorts, charge battery, with a helper, and ground connection snug but can slip off easily, turn key on, after a few seconds start turning things on one by one each after a few seconds, if any wire starts smoking you can slip ground strap off and fix this before you burn something up. lastly start engine and let charge w/everything on, make sure again nothing is smoking.dont forget to tighten batt connection.

[jhax]

Thanks for the info. I attached the jumper cables to negative terminal on the battery and the bolt that holds the alternator to the top bracket. Held the throttle at about 1500-2000 rpms put the negative probe on my mutimeter on the negative battery terminal and the positive probe on the back of the alternator terminal going to the stater. 11.5V and dropping. *** this is irritating. Could it be possible that the refurb alternator I got is just ***?

Thanks,
Justin

[R.O.R-2.0]

Yes please. What would be the reason for that?
I have learned a technique, here I think, take out the injectors and watch the glow plugs work or not.

These glow plugs have a filament coiled up and can short out to the inside wall of the pencil. They still have low resistance but don't have the hot spot near the end where the injector sprays it. 

usually, once one glow plug goes out, it takes the rest with it in short order.

Please explain...

well, i sort of worded that wrong..

having one wont literally take out the rest, unless it is a dead short, and pops the glow plug fuse..

what i meant, is that usually when one glow plug goes out, the rest usually arent too far behind it..

its always wise to replace glow plugs in sets, unless the set in the engine is fairly new, and an injector ate the tip off of one, or something like that..

Bosch Duraterms are the shizznit btw, hands down one of the best GPs on the market today..

One of our moderators had left his on for over a half hour before, and all 4 still worked the next day!!

[8v-of-fury]

One of our moderators had left his on for over a half hour before, and all 4 still worked the next day!!

This was in 2010, all still work to this date in a daily engine. They have been left on for over 45 minutes a few times.. (failing solenoid)

[R.O.R-2.0]

One of our moderators had left his on for over a half hour before, and all 4 still worked the next day!!

This was in 2010, all still work to this date in a daily engine. They have been left on for over 45 minutes a few times.. (failing solenoid)

LMFAO...

thats just plain awesome!!