electrical and ignition Grounding The Cluster

[paulram]

Is the cluster grounded somehow without wiring?  I want to see if the ground in my cluster is causing the tach to jump but dont see a grounding wire.  Is it grounded through the harness?  Mounting studs?  Do you run a separate ground on your own?

 

http://www.my2002tii.com/how_to_dash_gauges.htm

 

Also, I have no cluster lighting at all but have oil/brights etc.  I need to check the bulbs but if the bulbs are good and my headlights work, how finicky is the dimmer switch to these lights?

 

At least in this car the interior wiring seems to be in good shape.

[PaulTWinterton]

Tach jumping. Just went through that. I too added a ground behind my cluster. I put a spade connector on one of the self-tapping screws and ran a wire to the ground bolt on the firewall. You'll see the ground with a large brown wire attached on the firewall behind and right of where the cluster goes.

It didn't fix the tach issue.

The tach can be affected by the distributor points gap and electrical connections within the distributor. Check your gap and the points spade connector.

[jimk]

Panel grounding is thru the harness.  Grounding problem is usually not in the harness but in the printed circuit board.  Ground pin is at 9oclock viewing the back of the panel pins and would pin in to the harness connector location that has the brown wire (brown for earth in Europe). I jumped from the grounding pin on the circuit board to each ground lug (then knurled  nob ) at the temp and fuel gauges, also on the circuit board, in 1972.

If I understand screws you described, they do not provide ground, just hold the instrument cluster/tach/speedo in the case.

The lamps don't seem to have a ground issue, but since your tach does,  the ground jumper should also connect to the tach ground.

Edited April 19, 2014 by jimk

[PaulTWinterton]

I (wrongly) assumed that the metal chassis, like the car, was a common ground.  I stand corrected.

[Mike Self]

Three thoughts:

A flickering tach can also be caused by a worn point plate in the distributor.  This is the part that the points are fastened to and moves back and forth to advance and retard the spark.  Should be able to get a new one from a Bosch dealer.

 

Best way to do an auxiliary ground to the instrument cluster is to locate the two little brass knurled nuts on the back side of the temp and gas gauges, then make a Y-shaped harness with ring terminals on the short legs of the Y.  Fasten them under the knurled nuts, then run the long leg of the Y to a convenient ground on the body--I used one of the heater box mounting studs.  Make sure the wire is long enough so you can reach in and disconnect it when removing the cluster.

 

The dimmer switch portion of the headlight switch is finiky, but make sure the fuse is good and clean.  Best way to test the switch is to remove it from the car and use an ohmeter to test across the terminals while turning the knob.  If it's not functioning properly, try cleaning with some electronic tuner cleaner (carbon tet) and try again.  If it still isn't working, you'll need to find another switch. 

 

cheers

mike

[Gil. H.]

Not meaning to hijack....., alright I'm high jacking the thread.

I was doing to instrument cluster maintenance yesterday and the instrument light that sits bottom between the temp/speedo is out. It's one of the circuit board powered lights. Does anyone have any experience troubleshooting these "printed" light sockets?

All other lights are fine, this one is the only one that's not working. 

I did the normal cleaning, etc.

Thanks.

[bruno615]

You're going to need a multimeter.  Follow the traces and check for voltage.

 

Not meaning to hijack....., alright I'm high jacking the thread.

I was doing to instrument cluster maintenance yesterday and the instrument light that sits bottom between the temp/speedo is out. It's one of the circuit board powered lights. Does anyone have any experience troubleshooting these "printed" light sockets?

All other lights are fine, this one is the only one that's not working. 

I did the normal cleaning, etc.

Thanks.

[eurotrash]

I like my gas gauge bouncing when I leave my turn signal on, ever since I added the euro signals, its the only way I know to turn them off!

 

 

Of course, Adjusting the canceling tab would help, but I always forget to do it..  wither way, the light hasn't flashed in years.

[mike472]

Not meaning to hijack....., alright I'm high jacking the thread.

I was doing to instrument cluster maintenance yesterday and the instrument light that sits bottom between the temp/speedo is out. It's one of the circuit board powered lights. Does anyone have any experience troubleshooting these "printed" light sockets?

All other lights are fine, this one is the only one that's not working. 

I did the normal cleaning, etc.

Thanks.

Get an ohmmeter and check the bulb for an open circuit. Either the light bulb is blown or the little tabs on the bulb socket need a slight bend outward so they make good contact with the printed circuit board. Sometime the act of unplugging and plugging them back in will make them come on. Belmetric has the bulbs. Look at the Penske BMW parts diagram for the type of bulb it is.

[McKinney]

The headlight dimmer switch was very finicky on my car. I took the whole switch apart and rebuilt it. It is very easy to do once you look it over but putting it back together can be a pain. The contacts inside mine were very greasy and didn't make contact with each other. After the rebuild the switch moves and clicks much better. It also fixed my instrument panel lights. They wouldnt come on before.

I tried to get a replacement switch from the BMW dealership and they wanted $250! I wish I took pictures and made a "how to". Anyone have a switch they want rebuilt? If you ship it to me I'll rebuild it and make a how to. Or I'll buy it from you as a spare

Yesterday I was cleaning electrical tabs and grounds with a wire brush in the engine bay. Afterward I drove to the store and my tach was jumping badly. I poked around and found that the tab on the back of the distributor with a black wire going to it was loose. I pinched the connecter on the wire down with some pliers so it attached much tighter and it fixed my issue. Maybe play with that connection and see if it helps. The wire to the distributor is black and mine had a black plastic housing over the connector itself.

Edited May 6, 2014 by McKinney

[GreenSwede]

My flickery tach was a bad coil - installed a new one, and all was good. But, before and after that, when I turn on the head lights my temp and fuel gauge raises a bit.. That I believe is a ground issue. Or the circuit board I.

 

I do have another cluster from last summers slaughter of a inka shell, with the bonus of a working odometer, laying around when I get the time.

Edited May 6, 2014 by GreenSwede

[Gil. H.]

Get an ohmmeter and check the bulb for an open circuit. Either the light bulb is blown or the little tabs on the bulb socket need a slight bend outward so they make good contact with the printed circuit board. Sometime the act of unplugging and plugging them back in will make them come on. Belmetric has the bulbs. Look at the Penske BMW parts diagram for the type of bulb it is.

Thanks, Did the normal checks with a multimeter and found no current. I think there's a break in the circuit, just need to find out where and solder.