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Tail light issue

Bronco1294

Jr. Member
Joined
Dec 27, 2016
Messages
66
75bronc, new Centech harness. Headlights on, rt. Rear is dim. Dim. On brakes. Turn signal dim. All work though. ?????
 

B RON CO

Contributor
Bronco Guru
Joined
Jun 29, 2016
Messages
2,413
Loc.
Statesville, NC
Hi, I would make sure you have a good ground at that tail lamp. If you have a multi meter you can check for 12 volts at the bulb socket. Good luck
 
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Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
99% bad ground.

Turn the hazards on and the headlights at the same time. Go back and check again. Bet you loose all light in that bulb when they both try to come on at the same time.
 
OP
OP
B

Bronco1294

Jr. Member
Joined
Dec 27, 2016
Messages
66
Ground seems good. Still an issue. I did find a disconnected ground in the engine bay- it loose on one end but the other is attached to the intake manifold behind the carb. Any idea?
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,835
Not battery ground. Bulb ground. Paint, corrosion, dirt can insulate the bulb base from being a good ground. Not limited to just the bulb to the socket, but anything from the socket to the battery ground can be bad. Yes, paint is an insulation.
 

JAFO

Bronco Guru
Joined
Dec 3, 2007
Messages
1,556
Loc.
Beaverdam
If you do not have a good ground for the light then you have a voltage divider circuit. Disconnect the +12 volt cable from the battery. Then check with the multi-meter using OHM setting for resistance from the ground wire on the light to the body at a known good ground on the body someplace you can reach with the meter lead. Should be zero ohms resistance. Or sometimes I connect a long wire from the battery ground and use that as my ground reference and see if there is resistance from various locations I expect to be grounded. You are wanting zero (or nearly zero) ohms to ground from points you expect are ground. Some multi-meters will show like .003 ohms, which is essentially zero ohms. If you are seeing ohms resistance to current flow then you have a voltage divider circuit in play and the bulb will not be seeing a full 12 volts across it.
 
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ransil

Bronco Guru
Joined
Sep 6, 2003
Messages
8,122
shitty ground x3
engine ground and frame /body ground are 3 different things.

grounds are independent of the centech harness. ( centech harness ground scheme is questionable at best)

ground scheme should be Battery- Engine , engine - frame and body.

I always weld a stud to the frame near the engine mount and inner fender.
battery goes to frame stud, then frame stud goes to engine bolt and body stud.
 

JAFO

Bronco Guru
Joined
Dec 3, 2007
Messages
1,556
Loc.
Beaverdam
A little more on grounding....as mentioned I did similar. I welded a 3/8" bolt to my frame. Also welded a bolt to the body (heads of the bolts). Then ran heavy braided ground cables from battery to frame and from body bolt to that frame bolt. The body, battery and chassis are definitely grounded together on my Bronco.
 

DirtDonk

Contributor
Bronco Guru
Joined
Nov 3, 2003
Messages
47,355
Regarding the not-charging issue though, what alternator are you using? Internal or external regulator?

Paul
 
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