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2 weird instrument cluster-related questions

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Numbersix

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Discussion starter · #1 ·
First, when I turn on the parking lights/headlights, my MFA oil temp reading will jump 3-10 degrees. I assume this is a voltage isolation issue?
Also, when I've been sitting in traffic for some time, with the car mostly idling, I've noticed that when you first apply a little throttle, the tach will jump significantly from 1-2 then fall back. After driving for a short time it'll stop doing this.
Neither concern me, but I'm definitely curious as to know if anyone else has seen the same? I know of other people that have the MFA issue, but anyone experienced the tach issue? I'm thinking of jerking the cluster out and cleaning all the contacts.
 
#6 ·
Re: 2 weird instrument cluster-related questions (SeattleGLI)

There is a voltage regulator on the back of the cluster. They usually don't give a problem, but I would start there. I don't beleive they are very much from the dealer. I could be wrong. If you are looking at the back of the cluster, it is on the upper right hand side, above the back of the speedometer. One or two screws hold it on. If that is not working, that could be your entire problem. As long you have found no other electrical of sensor problems of course. Just my two and a half cents. Later. Mav.
 
#8 ·
Re: 2 weird instrument cluster-related questions (SeattleGLI)

do you have a bentley? they have instructions on how to troubleshoot in the electrical system section.
hth
Bentley Volkswagon GTI, Golf, Jetta Service Manual
Electrical System
Testing Multifunction Indicator
"The multifunction indicator and its control unit are powered through the voltage stabilizer and the instrument cluster printed circuit. On some models there is an additional voltage input from the battery to the printed circuit. The control unit receives inputs for road speed, engine vacuum, oil temperature, outside air temperature, and engine rpm. It processes these inputs depending on the position of the multifunction indicator mode switch. For trouble shooting refer appropriate instrument cluster wiring diagram in CURRENT FLOW DIAGRAMS. When making voltage continuity checks of components wiring, do not forget to also test the printed circuit tracks from the wire terminal housing to the multifunction control unit.
...
...
...
A problem with only the oil temperature or average speed readouts points to a problem with the sensors, the printed circuit or the control unit."
 
#10 ·
Re: 2 weird instrument cluster-related questions (SeattleGLI)

I've never come across that fault before, as far as i'm aware the voltage stabilzer (the little 3 pin unit) only supplies voltage to the fuel and temp gauge so they don't fluctuate with battery voltage, i'd be more inclined to think it's a bad connection at the plug.
Having said that if cleaning the terminals doesn't fix it you might aswell try the stabilizer as it's the cheapest part and if it does fix it i'll have learned something.
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Andrew Ensom
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