Courtesy light switch problem.
Discussion
Background: I have recently had the fuse panel relocated to behind the passenger seat and the battery relocated to the boot.
Here's the issue I’m having...
I recently noticed that the courtesy light no longer lit when a door was opened. But I could switch the light on manually by putting the switch in the usual 'permanent' position.
However, I can hear a relay click from within the car when I open a door and then again from the delay relay about 30 seconds after I shut the door. So it would seem the delay relay is being energised and is releasing ok.
The lamp unit was cabled as follows:
A Black wire went to the terminal connected to the rim of lamp bulb. The other two wires (Purple and Purple/Red) were connected to the switched terminals (i.e. were selected by moving the switch).
So I put the multimeter across the wires in different combinations to determine which wire (if any) rose to 12v when the door was opened (i.e. delay relay was activated). What I found was confusing:
With the meter probes between Purple and Black, I got 12v continuous.
With the probes between Purple and Purple/Red, I got 12v with the door open, then it reduced to 0v approximately 30 secs after shutting the door.
With the probes between Black and Purple/Red, I got nothing.
This looked like the Purple wire was actually connected to the Earth! (possibly a misconnection during the rerlocation - but I have been assured that no connections were removed during the relocation).
But when I checked continuity with the meter between Purple and the rim of the cigarette lighter socket, which I assume is earth, it read open-circuit (i.e. not earth).
I then checked continuity from the Black wire at the lamp to the cigarette lighter rim, this gave me zero Ohms (i.e. confirming that the Black wire was indeed Earth).
So, it seems that the Earth is ok, but there's something strange happening with the feed to the Purple/Red wire (timer delay feed).
Here’s what I get with the multimeter's negative probe touching the rim of cigarette lighter socket, and the positive probe on the wires at the lamp:
Purple 12v continuous .
Purple/Red 0.02v, reducing to 0v after delay relay releases.
Any advice or suggestions welcome.
Thanks,
Paul
Here's the issue I’m having...
I recently noticed that the courtesy light no longer lit when a door was opened. But I could switch the light on manually by putting the switch in the usual 'permanent' position.
However, I can hear a relay click from within the car when I open a door and then again from the delay relay about 30 seconds after I shut the door. So it would seem the delay relay is being energised and is releasing ok.
The lamp unit was cabled as follows:
A Black wire went to the terminal connected to the rim of lamp bulb. The other two wires (Purple and Purple/Red) were connected to the switched terminals (i.e. were selected by moving the switch).
So I put the multimeter across the wires in different combinations to determine which wire (if any) rose to 12v when the door was opened (i.e. delay relay was activated). What I found was confusing:
With the meter probes between Purple and Black, I got 12v continuous.
With the probes between Purple and Purple/Red, I got 12v with the door open, then it reduced to 0v approximately 30 secs after shutting the door.
With the probes between Black and Purple/Red, I got nothing.
This looked like the Purple wire was actually connected to the Earth! (possibly a misconnection during the rerlocation - but I have been assured that no connections were removed during the relocation).
But when I checked continuity with the meter between Purple and the rim of the cigarette lighter socket, which I assume is earth, it read open-circuit (i.e. not earth).
I then checked continuity from the Black wire at the lamp to the cigarette lighter rim, this gave me zero Ohms (i.e. confirming that the Black wire was indeed Earth).
So, it seems that the Earth is ok, but there's something strange happening with the feed to the Purple/Red wire (timer delay feed).
Here’s what I get with the multimeter's negative probe touching the rim of cigarette lighter socket, and the positive probe on the wires at the lamp:
Purple 12v continuous .
Purple/Red 0.02v, reducing to 0v after delay relay releases.
Any advice or suggestions welcome.
Thanks,
Paul
Edited by chim666 on Monday 16th November 10:29
Thanks for that! 
That makes sense from my meter checks, but doesn't account for the 'original' wiring with the black on the single connection and the other two on the 'switched' connectors (unless somebody had swapped them around during the relocation work).
I'll have a play later.
ETA: Replaced the delay relay (Ford relay 85GG 13C718 AA yellow 5 pin, £20 from eBay). Nothing happened initially when I opened the door, but on the second try...bingo! I shall replace the door switches later.
That makes sense from my meter checks, but doesn't account for the 'original' wiring with the black on the single connection and the other two on the 'switched' connectors (unless somebody had swapped them around during the relocation work).
I'll have a play later.
Edited by chim666 on Monday 16th November 17:21
ETA: Replaced the delay relay (Ford relay 85GG 13C718 AA yellow 5 pin, £20 from eBay). Nothing happened initially when I opened the door, but on the second try...bingo! I shall replace the door switches later.
Edited by chim666 on Saturday 21st November 11:52
Update: I replaced both door switches. They looked ok, but I replaced them anyway - which made no difference at all 
I then turned to tracing the cables from the lamp through to the panel by the side of the passenger's seat. I found a connector, and gave it a wiggle (ooo matron) with the door open - but that didn't improve matters. So I unplugged it and reconnected it - and immediately the light came on!
Connected and disconnected it several times to clean up the connectors, and that seems to have sorted it!
If it happens again, I'm pretty sure the problem is with that connector, so a thorough clean with switch cleaner will be in order.
I then turned to tracing the cables from the lamp through to the panel by the side of the passenger's seat. I found a connector, and gave it a wiggle (ooo matron) with the door open - but that didn't improve matters. So I unplugged it and reconnected it - and immediately the light came on!
Connected and disconnected it several times to clean up the connectors, and that seems to have sorted it!
If it happens again, I'm pretty sure the problem is with that connector, so a thorough clean with switch cleaner will be in order.
chim666 said:
Update: I replaced both door switches. They looked ok, but I replaced them anyway - which made no difference at all
I then turned to tracing the cables from the lamp through to the panel by the side of the passenger's seat. I found a connector, and gave it a wiggle (ooo matron) with the door open - but that didn't improve matters. So I unplugged it and reconnected it - and immediately the light came on!
Connected and disconnected it several times to clean up the connectors, and that seems to have sorted it!
If it happens again, I'm pretty sure the problem is with that connector, so a thorough clean with switch cleaner will be in order.
Cool. I'm glad you got the problem solved. I then turned to tracing the cables from the lamp through to the panel by the side of the passenger's seat. I found a connector, and gave it a wiggle (ooo matron) with the door open - but that didn't improve matters. So I unplugged it and reconnected it - and immediately the light came on!
Connected and disconnected it several times to clean up the connectors, and that seems to have sorted it!
If it happens again, I'm pretty sure the problem is with that connector, so a thorough clean with switch cleaner will be in order.
All these little helpful tips, help so much.
Another one to remember!.
Cheers.
FoxTVR430 said:
Cool. I'm glad you got the problem solved.
All these little helpful tips, help so much.
Another one to remember!.
Cheers.
You're welcome mate.All these little helpful tips, help so much.
Another one to remember!.
Cheers.
I know that some people would say that re-seating plugs is not a methodical way of resolving a problem. But in this case, the multimeter did not provide me with anything sensible. In such cases, especially when cables/plugs etc are becoming 'tired' and perhaps as in this case, electrical connectivity could be marginal resulting in reduced current flow, then re-seating connections is not a bad thing to try.
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