Electrical issues when in gear

[Gary2000TJ]

When in drive electrical issues show up. Headlights go out. Dash lights go out. Blinker lights don't work and nothing showing on dash. Brake lights don't work or any body lights. Blower on heat/air slows way down. If in park all these things work but start to go out if I turn on the blower or the lights. Any kind of load affects it.


I've tested battery its good

Tested alternator-it's good

Cleaned grounds by each headlight.

Cleaned ground on fire wall that attaches via strap to hood

Cleaned ground by driver side door

Cleaned ground by passenger door

Tried to clean ground on motor near filter but couldn't do it well as it has an e Tex socket. Two piece. Backed out a little and brushed. Used a light tester and engine doesn’t cause light to illuminate.

Don’t see another ground


Online suggest replacing

MFS that controls lights and blinker

Headlight switch

both ordered.

Anything I’m missing that I should try.

 

[CharlesHS]

Start with the simple things first….
Remove the battery clamps and clean both the battery terminals and inside the cable clamp.
Trace the ground cable down to the engine and ensure it’s clean and tight.
There is a ground cable on the fire wall above the valve cover; ensure it’s clean and tight.
Let’s see IF you find any problems with these that may cure your problem.
IF you use you light tester and touch the engine ground bolt and the positive on the battery; the light should glow.
IF not…. You either have a dirty connection which I was talking about earlier or dirty ground cable.

 

[Gary2000TJ]

Start with the simple things first….
Remove the battery clamps and clean both the battery terminals and inside the cable clamp.
Trace the ground cable down to the engine and ensure it’s clean and tight.
There is a ground cable on the fire wall above the valve cover; ensure it’s clean and tight.
Let’s see IF you find any problems with these that may cure your problem.
IF you use you light tester and touch the engine ground bolt and the positive on the battery; the light should glow.
IF not…. You either have a dirty connection which I was talking about earlier or dirty ground cable.

Cleaned battery posts and inside/outside of clamps. Cleaned all connections to it. Used light as you suggested and it illuminates the bulb when touching the engine ground post.

Ground cable on fire wall cleaned. This got my flood lights near windshield working but they are wired differently than other things affected.

Everything works while in park but when I turn on heat and blower I can see big change in headlights and dash goes out.

Oddly enough putting on emergency brake improves it slightly.

While driving all dim dramatically and go out.

 

[Gary2000TJ]

Start with the simple things first….
Remove the battery clamps and clean both the battery terminals and inside the cable clamp.
Trace the ground cable down to the engine and ensure it’s clean and tight.
There is a ground cable on the fire wall above the valve cover; ensure it’s clean and tight.
Let’s see IF you find any problems with these that may cure your problem.
IF you use you light tester and touch the engine ground bolt and the positive on the battery; the light should glow.
IF not…. You either have a dirty connection which I was talking about earlier or dirty ground cable.

And thank you for your advice. I appreciate it.

 

[Gary2000TJ]

Slight update

The brake light does work and I have running lights on the back. I posted earlier that I didn’t but they do work.

Playing around with trying to cause the problem, which isn’t hard, pushing the brake causes the lights to dim on headlights, dash, and lights on shifter. Having the heat/AC on causes the same problems and increasing blower speed causes it.

 

[JasterMereel42]

Have you taken the Jeep to an auto parts store and asked them to test the alternator?

 

[CharlesHS]

When you say you tested the alternator; how did you test it?
Test battery voltage before starting the Jeep, start the engine and test battery voltage after a few minutes, test alternator output voltage, turn headlights on and test alternator output and battery voltages.
This will determine what your next step is.
The alternator charging is regulated by the ECU and battery temperature sensor in the bottom of the battery tray.

 

[NskLJ]

When you say you tested the alternator; how did you test it?
Test battery voltage before starting the Jeep, start the engine and test battery voltage after a few minutes, test alternator output voltage, turn headlights on and test alternator output and battery voltages.
This will determine what your bextcstep is.
The alternator charging is regulated by the ECU and battery temperature sensor in the bottom of the battery tray.

Check the power wire going to the primary junction box, check voltage at fuses in box when it is acting up.

 

[CharlesHS]

Check the power wire going to the primary junction box, check voltage at fuses in box when it is acting up.

I believe your response was meant for the Original Poster and not my response to the OP.

 

[hear]

When in drive electrical issues show up. Headlights go out. Dash lights go out. Blinker lights don't work and nothing showing on dash. Brake lights don't work or any body lights. Blower on heat/air slows way down. If in park all these things work but start to go out if I turn on the blower or the lights. Any kind of load affects it.

This is the smoking gun. If it's load related, I'm thinking alternator related, but could also be a bad ground somewhere, or a short to ground inside the harness. There is always a problem inside the wiring harness. It might not be your specific problem, but guaranteed you'll find something in need of repair.

I'd also start it and just disconnect the battery to see what happens. And verify the belt & pulleys are all in good shape.

 

[DuckNut]

Voltage regulator.

I do not know if those are able to be changed of if you have to buy a new alternator.

 

[NskLJ]

I believe your response was meant for the Original Poster and not my response to the OP.

Yes it was

 

[NskLJ]

When in drive electrical issues show up. Headlights go out. Dash lights go out. Blinker lights don't work and nothing showing on dash. Brake lights don't work or any body lights. Blower on heat/air slows way down. If in park all these things work but start to go out if I turn on the blower or the lights. Any kind of load affects it.


I've tested battery its good

Tested alternator-it's good

Cleaned grounds by each headlight.

Cleaned ground on fire wall that attaches via strap to hood

Cleaned ground by driver side door

Cleaned ground by passenger door

Tried to clean ground on motor near filter but couldn't do it well as it has an e Tex socket. Two piece. Backed out a little and brushed. Used a light tester and engine doesn’t cause light to illuminate.

Don’t see another ground


Online suggest replacing

MFS that controls lights and blinker

Headlight switch

both ordered.

Anything I’m missing that I should try.

Check the wire from the battery positive cable to fuse box under the hood

 

[Gary2000TJ]

Have you taken the Jeep to an auto parts store and asked them to test the alternator?

No, I just tested volts on batter while off, which was 12.5 I think and running with everything on was 14 something. I’ve just been reading the forums and watching videos on how to do stuff. I’m not sure if this kind of test is sufficient to tell if a problem.

 

[Gary2000TJ]

Check the wire from the battery positive cable to fuse box under the hood

Thanks I’ll check that next.

 

[Gary2000TJ]

This is the smoking gun. If it's load related, I'm thinking alternator related, but could also be a bad ground somewhere, or a short to ground inside the harness. There is always a problem inside the wiring harness. It might not be your specific problem, but guaranteed you'll find something in need of repair.

I'd also start it and just disconnect the battery to see what happens. And verify the belt & pulleys are all idisc

Voltage regulator.

I do not know if those are able to be changed of if you have to buy a new alternator.

Not sure what that is but I’ll look it up

 

[Gary2000TJ]

This is the smoking gun. If it's load related, I'm thinking alternator related, but could also be a bad ground somewhere, or a short to ground inside the harness. There is always a problem inside the wiring harness. It might not be your specific problem, but guaranteed you'll find something in need of repair.

I'd also start it and just disconnect the battery to see what happens. And verify the belt & pulleys are all in good shape.

What happens when you disconnect battery?

 

[DuckNut]

Not sure what that is but I’ll look it up

It is inside the alternator and only allows a maximum amount of electricity to be generated. Your symptoms are indicative of a bad regulator.

An auto parts store should be able to test it for you.

 

[Gary2000TJ]

Battery -12.89

Engine running everything on -13.99

Engine running in gear everything on -13.96-97

Battery Removed jeep still running.

When taking positive cable off I tucked it down against frame and it sparked

Put positive cable back on to take off negative because I can’t let it touch anything because spark

Taking negative cable and wrench hits bracket holding battery and sparks.

I take test light and put clamp on negative and touch the screw clamp things holding battery down and I get a weak light.

I touch ground on body near headlight and bulb weakly lights up

Touch body of jeep and get weak bulb light up.

I’ve got clamp on negative and touching grounds and it’s getting light. I put clamp on positive and repeat for same thing

 

[Gary2000TJ]

Check the power wire going to the primary junction box, check voltage at fuses in box when it is acting up.

I’ll try this soon