Map Light Stays On
- Thread starter Mick
- Start date
mr. fix it
Old Man with a Hat
weird one... You're not running a DRL kit on the car are you?
what about if you are sitting in the car not running but ignition on and then step on the brake pedal?
Mick
Active Member
No DRL kit. Tried that (thanks). Here's what I did notice this morning. Since my ammeter doesn't work, I bought a plug in voltmeter from NAPA for short term use. When the door lights come on, it dies. No power, no read out, no nothing.
Backflow. There's a ground off somewhere.
Mick
Active Member
So, somewhere between the door lighting and cigarette lighter? And I looked up "backflow". However, it was written in an ancient Sumerian dialect, which Google could not translate...
Like water, electricity will take the path of least resistance - hence power wanting to flow through a circuit with a ground missing or other continuity break (hence incomplete) that is tied into a common source with other circuits will "reverse course" and flow in unexpected directions. Results like lights coming on can occur.
A good example is when the tail light fuse blows, (which as we know is tied into the headlight swich curcuit along with the panel and dome lights and door switches), sometimes the dome light comes on when the brake pedal is pressed. The power in that circuit wants to go to ground but can't do it through the broken fuse, so it can "see a complete circuit" through the dome light curcuit due to a shared power source.
A good example is when the tail light fuse blows, (which as we know is tied into the headlight swich curcuit along with the panel and dome lights and door switches), sometimes the dome light comes on when the brake pedal is pressed. The power in that circuit wants to go to ground but can't do it through the broken fuse, so it can "see a complete circuit" through the dome light curcuit due to a shared power source.
Mick
Active Member
I see. After my fusible link blew, I decided to take a look at my fuse box. Here's how it looked. See the pink wire riding over the scorched terminal? Is this the kind of condition that could create the backflow?
Possibly. Regardless, clean that up, check the pink wire for rub through underneath to the scorched connector.
I'd still look for a break, corroded ground, or a pinch/short somewhere too.
There is a hidden circuit breaker (single barrel fuse holder) as described above - mine was taped into the secondary harness for the console lights and was NOT marked on the wire diagram. This was definitely factory though, and caused me no end if grief (including wacky door light backfliw with the brake pedal) until I went nuts, ripped it out and took all the wrap off the harness and found it. Very odd.
I expect you have a lot of extra switched courtesy/map/reading lights, lighters, yadda yadda in your car. I expect all that may need to be looked at.
I'd still look for a break, corroded ground, or a pinch/short somewhere too.
There is a hidden circuit breaker (single barrel fuse holder) as described above - mine was taped into the secondary harness for the console lights and was NOT marked on the wire diagram. This was definitely factory though, and caused me no end if grief (including wacky door light backfliw with the brake pedal) until I went nuts, ripped it out and took all the wrap off the harness and found it. Very odd.
I expect you have a lot of extra switched courtesy/map/reading lights, lighters, yadda yadda in your car. I expect all that may need to be looked at.
3175375
Senior Member
yes
Mick
Active Member
Thank you.Back to work!
I'm in agreement with Ross.
Step 1) Repair the known bad wire
Step 2) If no change.... ALWAYS go back to what was repaired/replaced last, before the problem existed.
Step 1) Repair the known bad wire
Step 2) If no change.... ALWAYS go back to what was repaired/replaced last, before the problem existed.
....If only the borders were open....
Mick
Active Member
Great thought!
Mick
Active Member
Here's the sequence, everything working prior:
1. Odometer quits.
2. Removed instrument panel, sent to Speedo shop.
3. Reinstalled, except for climate control unit.
4. Hook up battery.
5. Blows fusible link.
6. Thinking temp control cable must have touched back of ammeter.
7. Then check fuse box and find corrosion/burns.
8. Ammeter no bueno, nada, nyet, non.
9. Curse - A LOT
10. Fix damage in fuse box.
11. Replace fusible link.
12. All systems GO ( well, except for ammeter)!
13. Buy plug in volt meter until I figure ammeter problem (replace/circumvent).
14. Voltmeter works GREAT (well, except for door lights staying on, and then voltmeter dying).
15. Did notice that on initial cold start up, door/map lights behave; voltmeter functions normally. Seems that once wires heat up, the action begins.
16. In process of de-taping harness.
Here is how all the courtesy, dome, map lights operate on MOST MoPars. I say MOST, well, because that's just the way it was. I've even seen the factory wiring diagram colors not jive with what is actually on the car, on 100% original cars.
Pink wires to each lamp are hot, all of the time.
Yellow wires from each lamp go to a ground source.
In the case of the dome lamp the ground wire feeds to each door "plunger" switch. Open the door and the switch completes the ground circuit. On the map light the button does the same thing. You may need to disconnect each one, one by one, to remove the switch from the circuit.
The headlight switch also has a dome system ground going through it (Brown, which also tees into your rear map switches, and also tees into Yellow wires). If you unplug the switch wiring that will remove it from the circuit.
I have chased these issues myself for HOURS before. Sometimes an accessory wire has been mistakenly spliced into a Brown or Yellow wire. Other times I found the wrong bulb type in one of the sockets.
I don't know why it wouldn't do it cold, other than you MAY have 2 wires almost touching, and as the wring warms and gets flexible they rub.
Happy hunting!
Pink wires to each lamp are hot, all of the time.
Yellow wires from each lamp go to a ground source.
In the case of the dome lamp the ground wire feeds to each door "plunger" switch. Open the door and the switch completes the ground circuit. On the map light the button does the same thing. You may need to disconnect each one, one by one, to remove the switch from the circuit.
The headlight switch also has a dome system ground going through it (Brown, which also tees into your rear map switches, and also tees into Yellow wires). If you unplug the switch wiring that will remove it from the circuit.
I have chased these issues myself for HOURS before. Sometimes an accessory wire has been mistakenly spliced into a Brown or Yellow wire. Other times I found the wrong bulb type in one of the sockets.
I don't know why it wouldn't do it cold, other than you MAY have 2 wires almost touching, and as the wring warms and gets flexible they rub.
Happy hunting!
Mick
Active Member
Thank you, Devinism, for the tutorial. I will get back on it.
mr. fix it
Old Man with a Hat
now that you mention this, could it be as simple as the headlight switch interior light reostat being in the light the interior lights mode?
One click past make the dash lights as bright as possible position?
Mick
Active Member
No, sir - checked that, and on cold start no issues. The plug in voltmeter will first start displaying crazy numbers, then quits. Then the door light come on. If I flip the map light switch, the map light comes on and the door lights dim. Flip the switch to off, and the map light goes out, but the door lights come up full. This all started when I blew the fusible link.
mr. fix it
Old Man with a Hat
I sounds like a grounding issue at this point or as Ross suggests a back feed taking place thorugh your system.
Hoping that you find the issue. First thing if you haven't is to bypass that volt meter you installed and see what happens.
Mick
Active Member
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