Author Topic: Electrical problems w/ my mk1 (Read 4969 times)

red64chevelle · « **on:** November 26, 2007, 09:36:04 am »

I am having some problems with my 84 Jetta TD.

1. A really big parasitic load. It will drain the battery in about two hours.

2. No warning/glow plugs lights when starting car.

3. Gas gauge and temp gauge don't work.

Lastly, does anybody have a picture with what sensors on the engine are which ones? The Bentley manual is good, but without knowing phsically where the sensors are, I am at a loss.

The car was not taken care of, and I am trying to get it back to full operational status.

Thanks in advance.

burn_your_money · « **Reply #1 on:** November 26, 2007, 10:07:43 am »

post a picture of your engine bay and I'll try and identify the sensors for you.

To find the parasitic load remove 1 fuse, put your amp meter in and find the reading. Once you find which one's drawing test each of the components on that circuit

Vincent Waldon · « **Reply #2 on:** November 26, 2007, 06:54:30 pm »

Ah..... electrical gremlins on a VW.... who woulda thunk it ??!! ;-)

A parasitic load big enough to drain the battery in a couple of hours is a pretty big load... you'll need to ensure your ammeter can handle 10 amps at least, and I'd be inclined to start with the fuses of your bigger loads... but start with the stereo first (if you have one) since it is the most obvious to draw a load unnoticed... headlights stuck on are much more obvious for example !!

9 times out of 10 when both gauges on the cluster won't work it's the result of poor connections at the small voltage regulator they both share, or the regulator itself.... usually the former. The regulator is on the back of the cluster itself... I start by resoldering the socket to the circuit board and then the regulator to the socket... has *always* done the trick for me.

However you are also reporting no warning lights... so it could be a master ground to the cluster. Does anything work ?? Clock ?? Turn signals ?? High Beam indicator ? If all of this stuff is out it really really does sound like a grounding issue at the cluster itself... and that could take out the gauges as well.

red64chevelle · « **Reply #3 on:** November 27, 2007, 04:35:10 am »

Its pretty weird, for the last six months or so, the battery held its charge great. Its only been recently since the draw has started. I think it might have started when I replaced the Alternator. I will have to start there.

The Clock does function normally. The Fuel Gauge used to operate when all the warning lights did, but now it does not. The Temp Gauge has never operated since I bought the car.

I'll take a picture of the engine compartment today for the sensor locations.

clbanman · « **Reply #4 on:** November 27, 2007, 06:30:29 am »

If the problem started when you replaced the alternator, start there. Was it new, rebuilt, junkyard? Take it in to your local CT, Partsource or similar shop and have them test it. I had one years ago that had an internal issue that caused a similar problem. To prove this out, have your battery charged and disconnect the wiring to your alternator. If you can still start the car in two hours you've likely found the biggest culprit.

rabbit gti guy · « **Reply #5 on:** November 27, 2007, 06:36:49 am »

sorry to intrude...i dont have any help but i have a few of the exact same problems. what does the voltage regulator on the cluster look like? can i run a new external ground wire from the cluster?

Vincent Waldon · « **Reply #6 on:** November 27, 2007, 08:59:43 am »

Quote from: "clbanman"

If the problem started when you replaced the alternator, start there.

2X... a shorted diode would cause the alternator to act like a very large parasitic load (through the field windings).... and also impact the alternator's ability to recharge the battery.

red64chevelle · « **Reply #7 on:** November 27, 2007, 09:36:45 am »

I have a spare brush set/regulator. I'll take a look at that.

red64chevelle · « **Reply #8 on:** November 27, 2007, 06:45:10 pm »

I changed out the Glow Plug relay, it believe it was stuck on. I also swapped the X relay with a spare I had. The Glow Plug and Alt lights work again. Fuel gauge works as well. The Temp gauge light blinks, but the gauge does not move. I think that it might just be hooked up to the wrong sensor. Here are some pics.

burn_your_money · « **Reply #9 on:** November 27, 2007, 07:14:53 pm »

Picture 2 shows the GP temp sending unit as well as the temp gauge sending unit. They aren't identical but you can mix them up and get away with it. Sometimes there is also another sender on the side of the head below the oil pressure sender. It is also on a coolant flange. Just make sure 2 of the 3 sensors are hooked up and you should be good to go

Picture #3 is the oil pressure sending unit in the head. There may or may not be another one on the top of the oil filter mounting flange.