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Discussion Starter #1
Cari Alfisti,

I have quite a disturbing electrical gremlin with the interior lighting on a 1993 164.

When the car is in motion, the front upper central interior light comes on & off intermittently, and sometimes it flickers. The problem gets worse when going over bumps and potholes.

I realize this has to be something with a connection or faulty earthwire but after a whole day outside tampering with the electrics I havn't been able to solve the problem.

Here is what I already did:

1. Cleaned the fuse & relay box (the main one lower left side of panel), sprayed everything with contact spray and re-installed.

2. Loosened the lower flange under the box holding the connectors, disconnected all, cleaned and reconnected.

3. There's a control unit under the glove compartment responsible for the check controls and interior light delay - I noticed it is also responsible for the interior light delay when engine is running and doors are open. When I dismounted it, cleaned all connectors and played with the wiring it seemed to have solved the problem but alas, a short run and the problem persists.

The only thing I still suspect is that the door jamb switch is faulty, or otherwise it's wiring causes a circuit to remain open - BUT WHERE THE HE** ARE THE DOOR JAMB SWITCHES??? I havn't been able to figure that one out. This also puzzles me as I don't see any "DOOR AJAR" indication on the panel.

For now I removed the fuse so there's no front interior light at all.

Aiuuuutttoooooooooo!

Thanks for your responses.
 

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Door ajar and interior light switches are microswitches inside door latches inside doors. Must be one of them.
 

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I know that the Volvo 850/S70 uses a two stage switch. Maybe the 164 uses the same sort of thing. The Volvo switch goes bad and will leave the lights in the door and in the footwell on but not trip the overhead lamp nor the door ajar indicator on. I usually will cut the wire on the faulty part so my customer won't have to buy a 175.00 door latch assembly. I'll try to look up a wiring diagram tomorrow.

Paul
 

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Discussion Starter #4
Some Progess

Thanks Paul & Steve for the responses. I was indeed puzzled when I couldn't find the door jamb switch, and according to you it is possible to have the switch work partially.

In anycase I have solved part of the problem. The car had an old alarm installed, and a friend of mine told me today "did you ever think of checking that"? This reminded me that an open bonnet will sometimes cause the interior light to come on when the alarm is active.

Being the only option left in my book before going to the shop, I disconnected the old alarm. At some stage things got worse because the car wouldn't start! I reconnected some of the wires until I could start the engine again but threw away the alarm unit once I was sure it was not doing anything else.

Once done I noticed something semi-good happened:
The interior lights did not work at all... Why is that good? -

When I turned the key to the "on" position, everything worked perfectly.

This leads me to the temporary conclusion that there are -2- circuits of interior light in the 164, or at least 2 current sources: One that operates all the time and that has nothing to do with ignition, and the other that turns off the light and works the delay when the engine is running.

Thinking back when I was driving with the interior lights flickering, it was obvious that the control unit DID turn off the lights, it was just another source that kept trying to close circuit and turn them back on - that circuit was tampered with when they installed the alarm - or so it appears to be.

For the time being I do have functional interior lights but only with the ignition key in the "on" position. I think (I hope) that once I manage to clean all the old wiring and re-connect everything correctly, the 1st circuit will work as well.

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After that I'll turn to more satisfying things like fixing the A/C control panel... :p:(:rolleyes:
 

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Sounds like you have found the source of your problem, but two things spring to mind:

- If door latch microswitch/mechanism bad, then you would have door ajar red light on instrument panel for the affected door, at the same time as the interior light turning on

- Pushbutton switches in ceiling console may be flaky - some of mine seem to require a double-push to make contact; if sticky, I wonder if they may turn on going over bumps. Related trivia question: my switch legends illuminated in white (well, white/orange), and also white for the rear pillar reading light switches. I'm sure my previous (newer) 164 had the legends illuminated in green, so I think I'll change them. Maybe I have too much spare time :rolleyes:

When it comes to the A/C control panel, do share how you get on with it. I've just replaced the bulbs for the LCD displays ('91 model) - temp and clock - I think US models have external temp in place of the clock. Anyway the bulbs are in small black twist-holders with a screwdriver slot on the reverse, which you get to by taking the panel apart (four edge screws). I found the bulbs as a special part available from Repco (our automotive store), just a dollar or two each. If not available, you can desolder bulb carefully and replace.

I also like to remove all the panel 'keys' (buttons is an understatement!) and apply masking tape to the edges, with a dab of silicone grease (this is after repainting all the buttons with colour-matched paint). The masking tape takes out the small amount of sideways slack and gives the best 'feel'.

-Alex
 
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