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Model Specific Questions and Info => MK2 Golf/Jetta and Audi 5k => Topic started by: oblique on August 07, 2022, 06:54:39 am
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I found a burnt resistor after pulling my cluster, could explain why my tach is out. Its the one just under the voltage regulator - its so burnt i cant make out the stripes...anyone have a pic I can use for refernce?
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I might be able to get you a value from a cluster I have. It may be a CE1 though. Are all the other resistors of a similar value? Seems like the MK clusters I work on have the same resistor all along the bottom.
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There might be some info in the thread about converting the gasser tach to work on the diesel but I can't seem to find that thread in the FAQs.
I know it's there but search didn't provide any results.
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That FAQ will give you resistor values that are on the tach itself but not that one on the board where he mentions it. I will see what I can find on a CE 1 cluster I think is handy in the downstairs shop.
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Oblique, I looked at the back of the cluster I have and the voltage regulator is above the speedo and the foil wraps over the top towards the lights. Is this what you have?
The small resistor on the end is a red, red, black lined one meaning it is a 22-ohm resistor.
The next in line is a diode, then two more resistors that have an orange, red, and orange banding with a 5% gold band at the end.
Those would value out to be 32 K ohms if I am reading the bands and conversion chart correctly.
If your setup is different shoot a picture of it and post it.
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Hey guys, sorry for the late reply, I took off to Portugal for a while.
Here are the pics of the bad resistor, hopefully theres enough context for location,
(https://i.ibb.co/0Y3VWBQ/20220807-001521.jpg) (https://ibb.co/0Y3VWBQ) (https://i.ibb.co/P15689B/20220807-001403.jpg) (https://ibb.co/P15689B) (https://i.ibb.co/nMQvXBK/20220807-001751.jpg) (https://ibb.co/nMQvXBK)
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Let me take the laptop to the cluster and see if I can orient myself to your pictures show.
Whatever that is tied to got hot, a direct short I would expect, or a very heavy drain in order to melt that plastic film.
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Sorry, heres a better photo. With resistor removed.
(https://i.ibb.co/NpCTdt5/20220903-103942.jpg) (https://ibb.co/NpCTdt5)
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I am visually comparing the picture to what I have and they are not the same. You have more resistors than I have on my cluster. Going to say that mine is not a CE2. But I still would try a 22-ohm resistor in that spot as some of the same items on mine compare value-wise to yours.
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Found a photo of the correct cluster with resistor from a nice French gentleman on ebay.
(https://i.ibb.co/VBkWHbw/2022-09-07-123634.png) (https://ibb.co/VBkWHbw)
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red,red,black,brown.
Is that 220ohm or 2200 ohm?
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I think the last one is gold, so ORCoaster was correct at 22ohm.
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I shoved a 1/2watt in there hoping it doesnt explode, and floated it off the foil in case it does. Really hoping this brings my tach back to life.
(https://i.ibb.co/BGD1hbs/20220911-224334.jpg) (https://ibb.co/BGD1hbs)
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Looks good from what I see. Most of the resistors I use are just like that.
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Well, it burnt pretty much right away. I can't tell if it's because I turned the radio on but it took some seconds for the smoke to appear, I'm guessing it just took that long to heat up?
Anyway, how do I start diagnosing this, I don't think my Bentley has a diagram for the cluster foil circuits.
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Something is shorting out or pulling a heavy draw on that resistor. I am not sure what it is hooked to either. I don't have a good handle on the Bentley circuit diagram for the cluster.
Can you follow the foil lines to what it is supposed to be powering on the cluster? The use of a meter might be necessary to do that.
You might have luck following it to say a fuel gauge or temp gauge that is shorted out perhaps.
Keep trying. And keep us in the loop.
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Can you follow the traces to see where they go?
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I dug out the cluster I have and that resistor is connected to the voltage regulator and then goes to what looks like some other electronic thing with a hose barb on the back. Maybe tied to the cruise control?
Perhaps your voltage is too high coming off the chip. It would be a tough thing to get the plugs on and measure the individual points. Maybe prewire some take of wires to the chip and then measure below the dash with the plugs active?
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Only thing I can think of with a barb on the back is used for a vacuum gauge hooked up for a fuel mileage estimate.
Wouldn't/shouldn't have one on a diesel.
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Fatmobile, I got this cluster off Craigslist in a deal with a diesel MK1 cluster. I was thinking I might be able to get it up and running if I had the proper wiring diagram for it and some of the plugs that go in the lower corners.
I take the tachs out of gas clusters and convert them for diesel. I have a couple in the shed now.
This MK2 cluster is nicer looking and would really freak out someone seeing the high MPH number. Does this thing even go that fast? I like the 80 mph sweep actually. It puts the 60 mark right where I can see it best over the steering wheel center.
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Alright so i finished my TB job finally and started the car with the cooked resistor cluster. Worse than before, now my fuel and temp gauges dont work at all. I changed all 3 bulbs on the back but 1 is still out.
Also now my taillghts (and amber front lamps (not flashers)) are always on. The headlight switch operates the headlights as before but it had no effect on the rest...they are on as soon as ignition is on.
The PO did wire in a manual rad fan controller in the engine bay...theres a temp probe that goes into the rad and the electrics box with adjustment wheel screwed to the body...there's quite a few wires going different places.
Havent had a chance to pull the cluster and get readings...i can also alligator clip the old resistor leads and run wires outside the dash and probe those
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The voltage regulator that resistor tracks back to runs the fuel and temp gauges.
So it might be somehow shorting to ground.
ORCoaster some gasser clusters had an MFA,.. multi function something.
It was a switch/button on one of the stalks that switched the LCD window in the cluster to display things like MPG, air temp? etc.
My '87 Jetta GLI had it.
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I bet that is what I am missing from the equation for getting the little box to display any information. I see the white letters and can figure out the graphics for all those functions. Now I know how they were cued from the stalk on the steering wheel.
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Quick update on this, I swapped the regulator with this one: https://www.digikey.ca/en/products/detail/stmicroelectronics/L78S10CV/1165899
The output/input legs are reversed on this one so it has to be mounted upside down...some washers and a longer screw did the trick for heatsinking, etc.
Seems to be working, although fuel and temps seem to be reading a little low now. I cleaned up some of the grounds near the battery and engine as well as the leads around the starter but no change...this is odd because I think low readings are a result of too little resistance, correct?
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Could be low voltage on the same resistance that would cause low readings.
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Measure the voltage at the sender.
I think it's supposed to be around 11 volts but really not sure.
I'll have to check mine.
That should tell you if there are voltage drops at connections etc.
I think as resistance goes down, current increases and the needle goes up.
Have you checked the ground from the instrument cluster?
If a ground wire has voltage on it,..
it's not grounded.