Dim headlamps and no dash lights

Thread Starter

Purple Chrissy

Joined Nov 19, 2019
6
Over the years I have done automotive electrical maintenance, i.e., changing bulbs in various locations around our various vehicles. Now I have what not long ago seemed like a monumental task... automotive-electrical troubleshooting! I have more confidence today than I did six months ago. But any tips or suggestions would be greatly helpful. I will do my best to keep this thread up to date. The vehicle: 2000 Dodge Grand Caravan Touring.
 

dl324

Joined Mar 30, 2015
16,658
I assume you've checked the fuses associated with the dash lights. Have you verified that the switch for dimming the dash lights is working? No clue on dim headlights.. Does their brightness vary with engine speed?

I have a 2000 Chrysler Town and Country which I think is the Chrysler version of the Dodge Caravan.
 

Alec_t

Joined Sep 17, 2013
14,201
Unless you have electronic dimming of headlamps (unlikely?) I'd suspect a poor earth connection between chassis and battery. Try cleaning/remaking any earth connections between battery neg, chassis and engine block.
 

geekoftheweek

Joined Oct 6, 2013
1,179
Being the dash lights and head lights are generally on separate fuses and circuits I would start with the switch myself assuming the dash lighting fuse is good. A wiring diagram would for sure help. You could jump pins in the connector and find out for sure if there is an issue with the switch.

If you have a meter handy measure between the ground pin on the head lights and the ground terminal of the battery with the head lights connected and on. It should be at most probably .2 volts, but obviously 0 would be better. That would test @Alec_t's theory of a bad ground. Maybe also disconnect one headlight and see if that makes a difference.
 

SLK001

Joined Nov 29, 2011
1,549
+1 on a bad ground. Back in the day, I had a 1970 Chevy that kept breaking the emergency brake cable. I thought that it was rubbing against the drive shaft, but after crawling under and investigating, it couldn't have been the shaft because of where it was breaking. It turned out that every time the cable hit the body, it would spark, slowly eroding the wire until it finally "sparked" thru the cable. To smooth out the ride, most of the body is isolated from the chassis by rubber isolators, which also mostly isolated the chassis ground. The only time I got decent ground connection to the body was when the cable hit the body (the E brakes were part of the chassis). I finally fixed the problem with a heavy gauge cable from the engine to the body, thus connecting the two potentials.
 

Thread Starter

Purple Chrissy

Joined Nov 19, 2019
6
I assume you've checked the fuses associated with the dash lights. Have you verified that the switch for dimming the dash lights is working? No clue on dim headlights.. Does their brightness vary with engine speed?

I have a 2000 Chrysler Town and Country which I think is the Chrysler version of the Dodge Caravan.
The headlights do not dim or get brighter with the revs. I will recheck fuses and check a few ground connections.
 

dl324

Joined Mar 30, 2015
16,658
Do you have the same problem with high beams?

Measure the voltage across the low beam as close as you can get to the connector on the lamp; taking care not to short anything. At low revs, you probably won't get around 13.8V, but it should be above 12V.

Is the battery known to be good? I had a problem in my Explorer where the instrument cluster went dead, but headlights still worked. Had a bad battery and alternator. The bad battery probably took out the alternator.
 

Thread Starter

Purple Chrissy

Joined Nov 19, 2019
6
I checked the ground to the body and engine. The battery is on the left side of the car. I tested the right side on a bolt and found 14+ M ohms resistance. 6" from the body it was 14-17 ohms. Tomorrow in the daylight I will disconnect the ground cable on both ends. I will test the cable thoroughly and if satisfied I will clean both the body/frame point where it connects and the battery's negative terminal point.
 

bwilliams60

Joined Nov 18, 2012
1,442
What is your open circuit voltage on the battery(battery voltage)? What is the voltage across the bulb when the light is turned on? It should be near battery voltage. If not, measure the voltage drop on the ground circuit. Measure the voltage drop on the positive side. One of those four steps will give you an answer to your headlights. Good luck :)
 
Top