Isuzu SUV Forum banner
1 - 17 of 17 Posts

·
Registered
Joined
·
1,854 Posts
Discussion Starter · #1 ·
So, when I have the dome lights set to the auto position; as in, the light turns on when the doors are opened; the light is noticeably dimmer than when I put the dome switch to the middle, or manual position.

Wassup with that?
 

·
Registered
Joined
·
1,672 Posts
Jay,

The situation that when in "auto", the circuit must take the long way to get voltage to the dome light. It must go round trip to the door switches and back, a much longer distance than from a switch, ie;"manual" position at the dome light! A possible remedy is to check all your connections on the door switches and the wire from the door switch at the dome light. Also. check all ground connections, immediate to this circuit. You may end up refreshing some connections, even possibly replacing a frayed wire, where the current circuit is only completed by a single strand of a multi-strand wire, increasing resistance, dimming the light in the door actuated mode.

Hope this helps,

GB
 

·
Registered
Joined
·
7,284 Posts
gb89amigo said:
Jay,

The situation that when in "auto", the circuit must take the long way to get voltage to the dome light. It must go round trip to the door switches and back, a much longer distance than from a switch, ie;"manual" position at the dome light! A possible remedy is to check all your connections on the door switches and the wire from the door switch at the dome light. Also. check all ground connections, immediate to this circuit. You may end up refreshing some connections, even possibly replacing a frayed wire, where the current circuit is only completed by a single strand of a multi-strand wire, increasing resistance, dimming the light in the door actuated mode.

Hope this helps,

GB
Not quite.

Hot goes to the light.

Through the light, to the switch.

Turn the switch to off = no ground for the electricity to complete the circuit with.
Turn the switch to on = Through switch, directly to ground, right there.
Turn the switch to door = Through switch, to wire that splits and goes to the door switches.

Open a door, and the power now runs through the door switch to ground at the jamb.

Clean up the connections at the door jamb switch.
 

·
Registered
Joined
·
1,854 Posts
Discussion Starter · #4 ·
I'm no electrical rocket scientist so had to read through your reply a couple of times for it to sink in. Makes sense, but why would this increased resistance or frayed wires happen at all? I see no signs of mayhem. This is a California car, been babied, not altered. Could it be the bulbs?

What exactly is a 'refreshed' connection?

gb89amigo said:
Jay,

The situation that when in "auto", the circuit must take the long way to get voltage to the dome light. It must go round trip to the door switches and back, a much longer distance than from a switch, ie;"manual" position at the dome light! A possible remedy is to check all your connections on the door switches and the wire from the door switch at the dome light. Also. check all ground connections, immediate to this circuit. You may end up refreshing some connections, even possibly replacing a frayed wire, where the current circuit is only completed by a single strand of a multi-strand wire, increasing resistance, dimming the light in the door actuated mode.

Hope this helps,

GB
 

·
Registered
Joined
·
1,854 Posts
Discussion Starter · #5 ·
Clean up the connections at the door jamb switch.
How would I do this?

Selador said:
gb89amigo said:
Jay,

The situation that when in "auto", the circuit must take the long way to get voltage to the dome light. It must go round trip to the door switches and back, a much longer distance than from a switch, ie;"manual" position at the dome light! A possible remedy is to check all your connections on the door switches and the wire from the door switch at the dome light. Also. check all ground connections, immediate to this circuit. You may end up refreshing some connections, even possibly replacing a frayed wire, where the current circuit is only completed by a single strand of a multi-strand wire, increasing resistance, dimming the light in the door actuated mode.

Hope this helps,

GB
Not quite.

Hot goes to the light.

Through the light, to the switch.

Turn the switch to off = no ground for the electricity to complete the circuit with.
Turn the switch to on = Through switch, directly to ground, right there.
Turn the switch to door = Through switch, to wire that splits and goes to the door switches.

Open a door, and the power now runs through the door switch to ground at the jamb.

Clean up the connections at the door jamb switch.
 

·
Registered
Joined
·
7,284 Posts
Jay said:
I'm no electrical rocket scientist so had to read through your reply a couple of times for it to sink in. Makes sense, but why would this increased resistance or frayed wires happen at all? I see no signs of mayhem. This is a California car, been babied, not altered. Could it be the bulbs?
Time.

Corrosion builds up no matter what you do. You can only make it take longer

Pull the switch off of/out of the door jamb.

Use some emery cloth on the switch where it meets the metal of the door jamb.

Do the same to the metal of the door jamb.

Liberally coat both surfaces with silicone dielectric grease. (Plumber's grease from Lowes will do just fine.)

Put back together.
 

·
Registered
Joined
·
1,854 Posts
Discussion Starter · #7 ·
See, I KNEW you were one of, if not THE, resident electrical experts. Gb being the other.

Kidding aside, thanks for the advice. One of these days when I have time (I'm not retireded even though I'm un-employed) I'll tackle the job.

Selador said:
Jay said:
I'm no electrical rocket scientist so had to read through your reply a couple of times for it to sink in. Makes sense, but why would this increased resistance or frayed wires happen at all? I see no signs of mayhem. This is a California car, been babied, not altered. Could it be the bulbs?
Time.

Corrosion builds up no matter what you do. You can only make it take longer

Pull the switch off of/out of the door jamb.

Use some emery cloth on the switch where it meets the metal of the door jamb.

Do the same to the metal of the door jamb.

Liberally coat both surfaces with silicone dielectric grease. (Plumber's grease from Lowes will do just fine.)

Put back together.
 

·
Registered
Joined
·
1,672 Posts
Jay,

X2 what Selador said. I was not, obviously, familiar with the Trooper wiring and had not looked at mine! But, though your Troop is a California vehicle, it's also 22 years old! Stuff happens. As to the wire fray, over 22 years, it's possible! If, after checking all the points Selador pointed out and any required corrective measures taken, and still have problem, check for frayed wire between door jamb switch and dome assembly. As to the bulb, it's the same bulb in both cases! Only the wiring is different. As Selador pointed out time is against us all. Maintenance is periodically required.

Selador, thanks for the wiring correction.

GB
 

·
Registered
Joined
·
1,854 Posts
Discussion Starter · #9 ·
Thanks GB. Wiring is wiring, and problems/symptoms are probably common across all vehicles.

gb89amigo said:
Jay,

X2 what Selador said. I was not, obviously, familiar with the Trooper wiring and had not looked at mine! But, though your Troop is a California vehicle, it's also 22 years old! Stuff happens. As to the wire fray, over 22 years, it's possible! If, after checking all the points Selador pointed out and any required corrective measures taken, and still have problem, check for frayed wire between door jamb switch and dome assembly. As Selador pointed out time is against us all.

Selador, thanks for the wiring correction.

GB
 

·
Registered
Joined
·
7,284 Posts
Jay said:
See, I KNEW you were one of, if not THE, resident electrical experts. Gb being the other.
I'm no electrical rocket surgeon, either.

The simplest way to think about a circuit is exactly as the name says... It is a circuit.

A circle.

It has to start at the battery, and it has to end at the battery.

The power comes from the battery through the wires. It goes through switches, bulbs, motors, etc. It has to return to the battery, one way or another.

If you are having problems with a circuit, just find the path the electricity is supposed to take.... And fix whatever it takes, to make that electricity be able to return to the intended path.

The path in your case was...

From the battery, to the light bulb. Through the light bulb, to the switch. Through the switch to ground. Through the metal of the vehicle, (ground), back to the battery.

The position of the switch determines whether the electricity is going to be interrupted and not allowed to go to ground. Off. Go straight to ground. On. Or have to go through yet another switch, the door switch, to get to ground.
 

·
Registered
Joined
·
7,284 Posts
gb89amigo said:
Jay,

X2 what Selador said. I was not, obviously, familiar with the Trooper wiring and had not looked at mine! But, though your Troop is a California vehicle, it's also 22 years old! Stuff happens. As to the wire fray, over 22 years, it's possible! If, after checking all the points Selador pointed out and any required corrective measures taken, and still have problem, check for frayed wire between door jamb switch and dome assembly. As to the bulb, it's the same bulb in both cases! Only the wiring is different. As Selador pointed out time is against us all. Maintenance is periodically required.

Selador, thanks for the wiring correction.

GB
You are welcome.

I believe you have corrected me a time or two already. And will no doubt have the opportunity to do so again.

:D :D :D
 

·
Registered
Joined
·
1,672 Posts
Selador,

Jay is too kind and I don't recall being so presumptive as to correct any of your posts. Course I'm in the "old fart" stage now, and my memory does not serve as well as yesteryear, yesterday, ..............10 minutes ago! Wish I had your skills! They're enjoyed by forum readers for succinctness, patience, terrific photos and related narration. Least yee think I'm nuts, going to shut up now, more than 'nough said!

GB
 

·
Registered
Joined
·
4,823 Posts
don't forget when you open the door your also powering the light on the door as well as the other door thats closed(courtesy lights) that might make a difference
 

·
Registered
Joined
·
11,705 Posts
There's also greater resistance in the longer circuit.
 

·
Registered
Joined
·
217 Posts
To make a simple question/repair even more complex, there is an electrical phenomenon called "local action" which produces corrosion at the anodes of a battery in a DC circuit, and also at switch terminals. The gist of it being that it will corrode over time even in a zero humidity environment. If you've ever had to replace the primary cables from your battery to the starter you will see lots of corrosion on the copper if you strip the insulation off, even in areas that are never exposed to air/humidity. ( Thank you ITT Institute Class of '87) Just like lightning produces Ozone, so does electrical current near a junction, which oxidizes the copper. If I can think of anything even more arcane I'll produce a slide show with flow charts and diagrams. :blackeye:
 

·
Registered
Joined
·
4,823 Posts
Ricardo said:
Just like lightning produces Ozone, so does electrical current near a junction, which oxidizes the copper. :blackeye:
So...does this mean if we have an electric car rally at Grand Junction this will fix the hole in the atmosphere? :idea: ...if so I will now run for El Presidente... :mrgreen:

oops...hyjack off :p
 

·
Registered
Joined
·
217 Posts
Bansil said:
Ricardo said:
Just like lightning produces Ozone, so does electrical current near a junction, which oxidizes the copper. :blackeye:
So...does this mean if we have an electric car rally at Grand Junction this will fix the hole in the atmosphere? :idea: ...if so I will now run for El Presidente... :mrgreen:

oops...hyjack off :p
It would be a great start. What would be even better is mounting mobile Tesla coils on the roofs of the cars. And mounting 16 extra spark plugs in place of headlights with a battery of high performance coils. I'd vote for you, twice!! 8)
 
1 - 17 of 17 Posts
Top