[GotMojo]

Started happening a month or so ago.  I *think* i coincided with a fast-blink on left turn indicator but can't be sure.  That problem is intermittent and comes up with temperature or moisture changes (can't tell which one yet). 

All gauges appear to work correctly.  Dials light up.  I took the cluster out to replace what I thought was a burned out bulb but found that all the back lighting is LED.  Dimmer has no effect -- no intermittent flickering or signs of life.  This leads me to suspect a voltage regulator in the cluster.  Anyone have a similar issue?

2002 EV

[andrew]

When you say that the dimmer has no effect, do you mean that it does nothing or that it has no apparent defect?
If the former I would suspect the dimmer wheel.

Most of my diagrams concern the early vans, but the one I found with the T32 connector for the cluster (early vans had T28) shows pin 20 driving L75 which I think is the backlight you're talking about. Pin 20 connects to U1/14 on the back of the fuse box, which is internally connected to plug R/ pin 4. R/4 connects to the headlight dimmer.

It appears that the dimmer gets power from relay 10, which is the fog light relay on the A3/B4 platform cars. I think the dimmer gets power internally from the switch from R/5 when the lights are on. I'm not seeing any fuses involved, which is fun.

My guess based on this would be a replacement headlight switch. You can test this by checking the voltage at the green/black wire from the back of the headlight switch with the parking lights on (if the license plate lights are on, the cluster backlight should be too). Should vary between 5-12ish volts when turning the wheel. If not, jumper it to 12 volts and see if the cluster lights come on.

[GotMojo]

Turns out it was just a fuse.  #8 controls the left side markers.  I somehow missed the fact that the front light was out as well.  I think I missed the break in the fuse the first time I looked because of the shade of red that the plastic is made of.  I'm color blind and some reds really make things hard to see.  Grrr...

After a lot of digging and troubleshooting I discovered that the backlight for the cluster is also fused to the left side marker circuit.  The fast flash I noticed a while back appears to be a symptom of the root cause.  Something in the wiring was/is shorting and caused the bulb to appear faulty and eventually led to the blown fuse.  I'll deal with that one later. 

Thanks for the help.  I was sorely tempted to track down a euro switch to have a nice neat fog light controller.   Maybe on the next dash rip-apart session...

[mastersryan!]

Sorry for jumping in on this older thread. But I am having the same problem but my left signal is working perfectly. Also, my speedo/odometer have stopped working while it seems the rest of the cluster remains to work properly. This is in a 93' mv weekender 5cyl/5spd. Any advice?

[andrew]

Speedo is probably a cable issue. There are a few joints where the internal cable can spin, and even get rounded off.

[mastersryan!]

Speedo is probably a cable issue. There are a few joints where the internal cable can spin, and even get rounded off.

I will have to look into this further to inspect I guess. Any ideas about the cluster lights?

[andrew]

let me go look at my Bentley and trace it back a minute.

L10 cluster lights get power on T28/12 (pin 12 of the cluster plug). That goes through U1/14 to what the Bentley calls terminal h1. H1 powers lots of things including the lights in the rear widow defogger switch, so you can check power on it by observing those lights.

H1 gets power from R/4, which gets power from pin 58b of "Light Switch". This pin supplies power from the dimmer wheel, which it gets from pin 58e, which comes from fuse 3 (10 amp).

So, get a cheap/free multimeter from harbor freight (or find/buy/make a test lamp) and verify power at those locations. When you find that, say, 58e has power but 58b doesn't, you know the thing in between (i.e. the dimmer wheel) is defective.

It's usually fuses or bulbs though

[mastersryan!]

Thanks! I just picked up this van earlier this week, looks like my first "real" purchase should be the Bentley!

[andrew]

The wiring diagrams are indispensable, but most other things you can mostly figure out yourself. Then again I don't have a gas engine anymore so that part is useless

[mastersryan!]

let me go look at my Bentley and trace it back a minute.

L10 cluster lights get power on T28/12 (pin 12 of the cluster plug). That goes through U1/14 to what the Bentley calls terminal h1. H1 powers lots of things including the lights in the rear widow defogger switch, so you can check power on it by observing those lights.

H1 gets power from R/4, which gets power from pin 58b of "Light Switch". This pin supplies power from the dimmer wheel, which it gets from pin 58e, which comes from fuse 3 (10 amp).

So, get a cheap/free multimeter from harbor freight (or find/buy/make a test lamp) and verify power at those locations. When you find that, say, 58e has power but 58b doesn't, you know the thing in between (i.e. the dimmer wheel) is defective.

It's usually fuses or bulbs though

AWESOME! Thanks for taking the time to look this up for me, huge help! I will try and attack this tonight when I get home from work.

[andrew]

No problem!

I just remembered another cause of no speedo/odometer: there is a small gear on the inside of the cluster speedo module (I want to saw a white or red worm gear) that can slip on its spindle. I had to simply push mine on more firmly to solve the problem.

I have a Passat electronic cluster now, though. If I get a chance and your cable seems fine I will try to find my old cluster and take a photo. Unfortunately the cluster has to come off for this, which requires removing the steering wheel and a 24mm deep socket.

[mastersryan!]

No problem!

I just remembered another cause of no speedo/odometer: there is a small gear on the inside of the cluster speedo module (I want to saw a white or red worm gear) that can slip on its spindle. I had to simply push mine on more firmly to solve the problem.

I have a Passat electronic cluster now, though. If I get a chance and your cable seems fine I will try to find my old cluster and take a photo. Unfortunately the cluster has to come off for this, which requires removing the steering wheel and a 24mm deep socket.

Yeah I am not afraid to take off the steering wheel to look at the module. Do you know if access to the speedo cable is behind the cluster or in the bay?

[andrew]

Cable access is a little of both, there are multiple sections that connect together. One connection is in the engine bay near the firewall— on mine, this connection slid apart one day without unscrewing causing the speedometer to be erratic and then stop working. It wasn't fully disconnected, but the internal cable had stopped driving the next section.