Electrical Advice Please

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tatkins101
E30 Zone Newbie
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Joined: Wed Apr 03, 2019 2:12 pm

Sun Apr 14, 2019 7:22 pm

Hi,

Picked up my first E30 5 days ago, been 5 of the most enjoyable days since. BUT, there is clearly an electrical issue, advice on the following would be greatly appreciated.
1. Tacho/ Eco not working. Speedo Fuel and Temp all work fine but temp, eco and tacho have no backlighting.
2. Radio doesn't turn on.
3. Interior lights dont turn on
4. Central locking not functioning properly, can lock car fine from inside, key turns in door but doesn't lock.

I understand that electrical faults can be linked together, not sure if these are or are separate issues. Have replaced all necessary fuses but resolved nothing.

Ta :drive:
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Brianmoooore
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Joined: Mon Jan 10, 2005 11:00 pm

Sun Apr 14, 2019 9:45 pm

Fairly confident these are all unrelated issues.

1/ There are two lamps that illuminate the cluster, via plastic light guides. These are in the two larger holders on the back of the cluster, and one of the lamps has failed. They are 3W 12V capless, which must be used - not the more readily available 5W 12V ones. If you use 5W, things WILL melt.

Although the tacho and Eco share the same housing, they are completely separate gauges. No common fault that affects both of them, so I'd start by checking all is well with the pins and socket that plug the assembly into the main circuit board.

2/ This could be anything. Wouldn't be the first that I've seen where the radio has had no connections to it at all, and is just filling up the gap in the dash. A radio should be connected to a four wire loom that plugs into the accessories socket behind the glovebox area, but your car is likely to have had a few aftermarket installs since it was new, and they could be wired in any one of several dubious ways. You'll have to pull the radio out, and see what sort of mess is behind it.

3/ Don't light at all, or don't light when the front doors are open? There's a three position switch on each light - permanently on, permanently off, switch by doors. Check the switch position (and whether there are lamps fitted.)

4/Do you mean that the car unlocks from outside the car but doesn't lock? Does this happen with both doors and the boot? If you lock/unlock a door from the inside, does this lock/unlock the other doors and boot as well?
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tatkins101
E30 Zone Newbie
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Joined: Wed Apr 03, 2019 2:12 pm

Mon Apr 15, 2019 9:33 am

Thanks for the reply.

Sorry I wasn't totally clear, the Tacho/ Eco do not work at all, not just the lighting issue. I have researched it a bit and SI batteries seem to be the issue.
Regarding the radio what should I be looking for when taking it apart? Damage to the loom? connection issues? anything else?
The door locks all lock from the inside, but cannot lock from outside the car so I dare not lock it and close the doors. Not sure if this is electrical or mechanical.

Ta
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Brianmoooore
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Mon Apr 15, 2019 7:18 pm

SI board batteries readily affect the tacho. (and temp.gauge), but not usually the eco. gauge, unless the problem is that the batteries have leaked corrosive juice over the SI board onto the eco. gauge circuitry nearby. If the batteries are dead, you should have issues with the SI LED display as well.
If the radio is anything other than the one fitted from new, then any conceivable type of bodge up could be behind it. An observation of the general standard of the work would be a starting point.
Not all E30s had central locking, but assuming yours has, then what you say is common when the electric locking fails. The locks should work mechanically, but after 30 years of not being lubricated and being normally assisted by motors, they become to stiff to work from the key without that assistance.
Remove the panel in front of the 'speaker in the driver's foot well, remove the 'speaker, the little plastic piece below it inside the sill, the two cross head screws directly below the 'speaker, and lift out the locking ECU, complete with its mounting bracket, from its hiding place deep inside the sill. Unplug the locking ECU and connect a 12 volt lamp of at least 5W between the brown wire and the red/black wire, and see if it light at full brightness.
Don't put it all back together before reporting back.
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