Map Light Switch Question
#1
Map Light Switch Question
Well, it's starting. I have the '91 convertible home and in the garage. ROM on order. Experience in a Book read so many times it's almost memorized. Ready to bleed brakes, change all hoses and belts, and otherwise trying to figure out what I have, and what I need to do.
Actually, first order of business is to get rid of the mothball smell. It seems the PO was nervous about mice. At first, I thought the trunk smelled like gas (and I'm still looking for the charcoal canister), but that will be solved in time. Meanwhile, back in the cockpit:
My map lights do not work. I tested the bulb, so I know it's not that. Pulled the switches from the dash.
I know I have power to the switch, because I can see the switch light turn on with the headlights. I don't know if there is actually power to the switch itself, or how to check it. There is a red and black wire in the centre of the switch block. I could not get a voltage reading across these two wires, but did get zero resistance between the two. I can't tell if these wires power the switch, or just the bulb in the switch.
When I pulled the switch out, there seems to be a "block" of (if memory serves) purple wires going to the bulb. Continuity check shows this part to be good.
However, continuity within the switch itself does not seem to be there, on or off. But it seems odd that two map light switches are both blown, but all other switches (defogger, hazard, windows, top, cruise control, even the heated seats and lumbar support) work flawlessly. Am I doing something wrong in testing? Chasing shorts is new to me. Suggestions before I just buy switches and throw money at the problem?
Actually, first order of business is to get rid of the mothball smell. It seems the PO was nervous about mice. At first, I thought the trunk smelled like gas (and I'm still looking for the charcoal canister), but that will be solved in time. Meanwhile, back in the cockpit:
My map lights do not work. I tested the bulb, so I know it's not that. Pulled the switches from the dash.
I know I have power to the switch, because I can see the switch light turn on with the headlights. I don't know if there is actually power to the switch itself, or how to check it. There is a red and black wire in the centre of the switch block. I could not get a voltage reading across these two wires, but did get zero resistance between the two. I can't tell if these wires power the switch, or just the bulb in the switch.
When I pulled the switch out, there seems to be a "block" of (if memory serves) purple wires going to the bulb. Continuity check shows this part to be good.
However, continuity within the switch itself does not seem to be there, on or off. But it seems odd that two map light switches are both blown, but all other switches (defogger, hazard, windows, top, cruise control, even the heated seats and lumbar support) work flawlessly. Am I doing something wrong in testing? Chasing shorts is new to me. Suggestions before I just buy switches and throw money at the problem?
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When I pulled the switch out, there seems to be a "block" of (if memory serves) purple wires going to the bulb. Continuity check shows this part to be good.
However, continuity within the switch itself does not seem to be there, on or off. But it seems odd that two map light switches are both blown, but all other switches (defogger, hazard, windows, top, cruise control, even the heated seats and lumbar support) work flawlessly. Am I doing something wrong in testing? Chasing shorts is new to me. Suggestions before I just buy switches and throw money at the problem?
However, continuity within the switch itself does not seem to be there, on or off. But it seems odd that two map light switches are both blown, but all other switches (defogger, hazard, windows, top, cruise control, even the heated seats and lumbar support) work flawlessly. Am I doing something wrong in testing? Chasing shorts is new to me. Suggestions before I just buy switches and throw money at the problem?
You're not doing anything wrong, per se. The interior light circuits are a bit fiendish---more so than most cars. When you see the diagram you'll know what I mean. It's a tricky circuit to figure out.
I do know that the solid purple wires are voltage directly from the fuse. Purple/white are grounds from the door switches. I think the other purple/xxx combinations are voltage from a switch.
Hopefully someone can post a '91 diagram for you.
Convertibles are different then coupes, by the way, in terms of the interior light circuits
Cheers
DD
#6
You're not doing anything wrong, per se. The interior light circuits are a bit fiendish---more so than most cars. When you see the diagram you'll know what I mean. It's a tricky circuit to figure out.
I do know that the solid purple wires are voltage directly from the fuse. Purple/white are grounds from the door switches. I think the other purple/xxx combinations are voltage from a switch.
Hopefully someone can post a '91 diagram for you.
Convertibles are different then coupes, by the way, in terms of the interior light circuits
Cheers
DD
I do know that the solid purple wires are voltage directly from the fuse. Purple/white are grounds from the door switches. I think the other purple/xxx combinations are voltage from a switch.
Hopefully someone can post a '91 diagram for you.
Convertibles are different then coupes, by the way, in terms of the interior light circuits
Cheers
DD
What I don't understand is which "pins" the switch activates. It seems that I should get some continuity between pins when the switch is in, but I can't figure out which.
As far as checking relays, that makes sense... but I'm not sure where they are hiding.
#7
Thanks. It sounds like a tricky circuit, and I did notice that "switch 2" has a different number of wires leading to it than "switch 1".
What I don't understand is which "pins" the switch activates. It seems that I should get some continuity between pins when the switch is in, but I can't figure out which.
As far as checking relays, that makes sense... but I'm not sure where they are hiding.
What I don't understand is which "pins" the switch activates. It seems that I should get some continuity between pins when the switch is in, but I can't figure out which.
As far as checking relays, that makes sense... but I'm not sure where they are hiding.
Also, check if you have power to the door jamb switches, by unscrewing the unit and carefully pulling out the switch. Purple is power, black is earth on the switch. Also check that the earth does earth.
On my car (pre facelift) the fuse for these lights is No 13 in the auxiliary fuse box, which is below the dash on the passenger side 9you may have to remove the knee/shin trim to get to it, maybe not, 10 amp fuse. Check this first? Note that one switch on the dash does the rear lights, and one the front lights, but ONLY the passenger map light is activated by the front switch, not the driver's side.
Greg
Last edited by Greg in France; 03-01-2016 at 06:23 AM.
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#8
On the 90-91 conv. there is a relay like component called the "delay unit" which must have been what I was thinking about. It is located in the right component panel.
A word of caution the schematics for interior lighting are mislabeled in the Electrical Guide. The Coupe schematic is actually the Conv. one.
I've attached the schematics
Last edited by Mac Allan; 03-01-2016 at 10:50 AM.
#9
Thank you for the schematic, I will ponder it.
Greg, thank you, yes, fuse. On this pre-facelift convertible, there is no centre light, but there are two in back. I need bulbs for those.
The diagram in the fusebox specified a 5 amp fuse, and it was blown. I did not have a five amp, but conveniently located in the panel cover was a 4 amp. Worth a try until I can get a five tomorrow, and better than the 15 and 30 spares next to it.
Popped it in, and both map lights and the puddle lights in the doors turned on. Good so far.
Got in, made sure the doors were closed. Delay circuit worked, after a pause, the lights went out. Now we are getting somewhere.
But.
Turned on switch #1 (left most switch). No light on the left, light on the right on.
Turned off switch #1, and turned on switch #2. I half expected either the left light to come on, or perhaps both lights. Instead, no lights with switch #2.
Open the doors, both lights and puddle lights on. Closed the doors, delay works. Went through the whole loop several times, same result.
Bottom line: Switch #1 lights the right light. No lights with switch #2.
Thoughts?
Greg, thank you, yes, fuse. On this pre-facelift convertible, there is no centre light, but there are two in back. I need bulbs for those.
The diagram in the fusebox specified a 5 amp fuse, and it was blown. I did not have a five amp, but conveniently located in the panel cover was a 4 amp. Worth a try until I can get a five tomorrow, and better than the 15 and 30 spares next to it.
Popped it in, and both map lights and the puddle lights in the doors turned on. Good so far.
Got in, made sure the doors were closed. Delay circuit worked, after a pause, the lights went out. Now we are getting somewhere.
But.
Turned on switch #1 (left most switch). No light on the left, light on the right on.
Turned off switch #1, and turned on switch #2. I half expected either the left light to come on, or perhaps both lights. Instead, no lights with switch #2.
Open the doors, both lights and puddle lights on. Closed the doors, delay works. Went through the whole loop several times, same result.
Bottom line: Switch #1 lights the right light. No lights with switch #2.
Thoughts?
#10
#11
#12
Thank you for the schematic, I will ponder it.
Greg, thank you, yes, fuse. On this pre-facelift convertible, there is no centre light, but there are two in back. I need bulbs for those.
The diagram in the fusebox specified a 5 amp fuse, and it was blown. I did not have a five amp, but conveniently located in the panel cover was a 4 amp. Worth a try until I can get a five tomorrow, and better than the 15 and 30 spares next to it.
Popped it in, and both map lights and the puddle lights in the doors turned on. Good so far.
Got in, made sure the doors were closed. Delay circuit worked, after a pause, the lights went out. Now we are getting somewhere.
But.
Turned on switch #1 (left most switch). No light on the left, light on the right on.
Turned off switch #1, and turned on switch #2. I half expected either the left light to come on, or perhaps both lights. Instead, no lights with switch #2.
Open the doors, both lights and puddle lights on. Closed the doors, delay works. Went through the whole loop several times, same result.
Bottom line: Switch #1 lights the right light. No lights with switch #2.
Thoughts?
Greg, thank you, yes, fuse. On this pre-facelift convertible, there is no centre light, but there are two in back. I need bulbs for those.
The diagram in the fusebox specified a 5 amp fuse, and it was blown. I did not have a five amp, but conveniently located in the panel cover was a 4 amp. Worth a try until I can get a five tomorrow, and better than the 15 and 30 spares next to it.
Popped it in, and both map lights and the puddle lights in the doors turned on. Good so far.
Got in, made sure the doors were closed. Delay circuit worked, after a pause, the lights went out. Now we are getting somewhere.
But.
Turned on switch #1 (left most switch). No light on the left, light on the right on.
Turned off switch #1, and turned on switch #2. I half expected either the left light to come on, or perhaps both lights. Instead, no lights with switch #2.
Open the doors, both lights and puddle lights on. Closed the doors, delay works. Went through the whole loop several times, same result.
Bottom line: Switch #1 lights the right light. No lights with switch #2.
Thoughts?
Other than LHD verses RHD mine do the same.
#13
New bulbs for the back are on the list for today. We shall see. I am at a loss as to why missing bulbs would shut the whole system, as that would mean they are in series and not parallel. Additionally, they are on rocker switches that may be off, off when the door is closed but on when open, or on, so if they were in "off" position the switch on the dash would never do anything, but I may be over-thinking it. Either way, I've learned something. The most important point: "First principles, Clarice..."
#14
#15
So what we learned today is that the "interior light switch" works the back lights.
My drivers side switch is actually broken internally, which is why there was no bulb.
Passenger side had a bulb, but "something" was not right in the wiring. Difficult to explain, but the repair obviously went wrong.
Pulled the duct tape (yes, duct tape) on the PO repair, spliced and soldered in a new wire, end now it works as it should. I still think the map light switch should be closer to the passenger, but that's the way it is.
My drivers side switch is actually broken internally, which is why there was no bulb.
Passenger side had a bulb, but "something" was not right in the wiring. Difficult to explain, but the repair obviously went wrong.
Pulled the duct tape (yes, duct tape) on the PO repair, spliced and soldered in a new wire, end now it works as it should. I still think the map light switch should be closer to the passenger, but that's the way it is.
#16
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