Gauge cluster wiring and lighting

[BaaderMeinhofWagen]

Finally got around to pulling the gauge Cluster to troubleshoot the odometer but in so doing discovered a missing bulb socket for one of the idiot lights behind (L charge I think) and and a damaged white larger bulb socket from one of the tach illumination bulbs.

Also found those lights to be wired with an extra ground wire for some reason. 

Anyone know a source for those bulb holders?

TIA

[John76]

You might be able to find a bulb holder from "a hoarder of parts" on this forum. That describes me, but I don't have a spare dash module. 😒

The metal part of your speedometer back has a ground cable with connector but add ground wires from the knurled nuts on the back of the coolant and gas gauges. This will really help solve the bouncing needle syndrome.

 

[BaaderMeinhofWagen]

Thanks,

I like the idea of the added grounds,

👍🏼

[jimk]

23 minutes ago, BaaderMeinhofWagen said:

Thanks,

I like the idea of the added grounds,

👍🏼

So long as it is confrimmed the speedometer back is grounded.  It has no dedicated ground path.

[BaaderMeinhofWagen]

Further to my query, anyone know what the double brown with black striped wire is for? It wasn't connected to anything when I pulled the gauge cluster. My understanding is that there was no dedicated ground wire to to cluster.

[John76]

Looks like the Brown/black connector goes to your dash pod ground.

The Black connector (above on right) comes from the distributor and goes to the tach and diagnostic plug #9.

 

[BaaderMeinhofWagen]

Yup tach wire is accounted for but the black wire with female termination you circled wasn't connected to anything and the brown/black wire also female is part of the wiring loom from the firewall was also not connected to the gauge cluster. There is no male spade connector anywhere on the back of the cluster it would normally go to anyway. My wiring diagrams so far don't yield any insight yet either..

[John76]

If that Brown/black is part of the original harness (not added by a PO) it might be the connection to the Fasten Seat Belt pod on top of the dash. Usually, BMW uses a Brown wire with a colored tracer (black in your car) as a switch-controlled ground wire.

The black wire on your dash pod looks like the PO added this as the dash ground. One end connects to the left-bottom screw of the metal case for the tach. It continues to a dash bulb ground tab, and then to the female connector.  

Easy to check the grounds for continuity with a meter. 

I make sure everything on the dash pod is grounded and then connect it with a wire to the ground post near the heater (under the dash).

[jimk]

11 hours ago, BaaderMeinhofWagen said:

My understanding is that there was no dedicated ground wire to to cluster.

The dedicated ground wire is in the harness plug, brown wire.  It's not what often causes the fuel/temp gauges to read high, that problem is in the printed circuit board ground trace for those instruments.  If the cluster lights work, the harness ground is good.

['76mintgrün'02]

You could add a tab like this one for your double-brown grownd-wire.

 

[BaaderMeinhofWagen]

Thanks for the responses gents. I'm going to connect those knurled knobs for the gauges to a dedicated ground wire that I will attach to either the heater box bolt or drill my own hole right behind the cluster.

The question remains is what is this loose mystery brown/black wire beside the black plug in my picture above.

 

[Henning]

3 hours ago, BaaderMeinhofWagen said:

Thanks for the responses gents. I'm going to connect those knurled knobs for the gauges to a dedicated ground wire that I will attach to either the heater box bolt or drill my own hole right behind the cluster.

The question remains is what is this loose mystery brown/black wire beside the black plug in my picture above.

 

On Euro cars with one-barrel carburetor this is for the manual choke. Lits the red central control when pulled what is also for fuel reserve and e-brake.  Can hardly be seen in the pic behind the blue choke cable- sorry, I don't have a better one.

henn

[BaaderMeinhofWagen]

Mine is a 75 euro spec'ed car. There's no manual choke so a red herring then I guess?

[John76]

Ahhh, a euro spec square light!

@Henning was right!

Any of the indicated items on your picture will cause the red light on the instrument pod to light up.

 

[BaaderMeinhofWagen]

2 hours ago, John76 said:

Ahhh, a euro spec square light!

@Henning was right!

Any of the indicated items on your picture will cause the red light on the instrument pod to light up.

 

Noted thanks. Interesting that this cable exists but there is no manual choke on this particular car. Just to make things more mysterious is that this car was imported from Japan a year ago.

No it isn't RHD but the ecode headlight beam pattern is for Left-hand traffic.

If anyone is interested in a JDM rear licence plate mount with side illumination let me know.