Troubleshooting Lockers

Rut Row

Rut Row

Geezer in Training
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Joined
Nov 29, 2022
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274
Location
North of Keedysville, MD
Per the 2003 Service manual regarding diagnosing locker issues:

(6) Disconnect the rear and/or front locker indicator switch pigtail harness connector from the rear or front axle jumper harness connector. Check for continuity between the ground circuit cavity of the rear or front axle jumper harness connector and a good ground. There should be continuity. If OK, go to Step 7. If not OK, repair the open ground circuit between the rear or front axle jumper harness connector for the rear or front locker indicator switch and ground (G105) as required.

(7) Check for continuity between the ground circuit and the rear or front locker indicator switch sense circuit cavities of the rear or front locker indicator switch pigtail harness connector. There should be continuity with the axle locker engaged, and no continuity with the axle locker disengaged. If OK, go to Step 8. If not OK, replace the faulty rear or front locker indicator switch.

I'm confused. What is the difference between the two? It seems to be saying the same thing except for engaging the lockers.

Also, how do you engage lockers that are not working?

(9) Check for continuity between the rear or front locker indicator switch sense circuit cavities of the rear or front axle jumper harness connector for the locker indicator switch and the instrument cluster. There should be continuity. If OK, use a DRBIIIt scan tool to perform additional testing of the instrument
cluster. Refer to the appropriate diagnostic information. If not OK, repair the open rear or front locker indicator switch sense circuit between the rear
or front axle jumper harness connector for the locker indicator switch and the instrument cluster as required.

This makes no sense to me. Am I checking between the locker switch and the instrument cluster? the locker switch? Both? Neither?

Can someone dumb this down for me?
 
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Rut Row said:
both locker lights flash when I press the locker switch once (for the rear locker). The 4WD light is on.
Click to expand...
1) Are the compressors coming on?
2) Are the compressors running continually?
3) Have the lockers been out like for a regearing?
 
I went back and double checked fuse 26 24. If you test it with the fuse installed, the fuse test fine. But if you remove the fuse from the fuse holder. One side tests hot at 12.8 volts, and the other side which should be 0 volts tests to 8.7 volts. When I replaced the fuse, the lockers worked perfectly.

Next question is should I worry about what appears to be a short in power to the locker relay? Everything appears to be working fine.
 
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The first thing to do is check is the air. Turn on ignition power without starting the engine. Turn on the lockers. Crawl under the Jeep and listen for the locker pumps. They sound like a fish tank aerator. If you hear them, then there is an air leak. Pull an air hose off a pump and cover the hole with a finger. If the pump shuts off, then there is a leak in the hose. Check both pumps.

FYI, the front will not pump until the rear has engaged.
 
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Rut Row said:
Next question is should I worry about what appears to be a short in power to the locker relay? Everything appears to be working fine.
Click to expand...

Per the FSM, that fuse feeds several things, not just the locker stuff. Any of those other components could be leaking a little voltage onto that wire. It may be a "phantom" voltage, not even able drive enough current to bother anything at all. I wouldn't worry about it.

If you're an electronics type, and had, say, a 1K resistor, you could connect it to the phantom side of the fuse socket and to ground (without the fuse), and then check it — the voltage would probably disappear, even with that light load (12 mA).
 
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OldBuzzard said:
Per the FSM, that fuse feeds several things, not just the locker stuff. Any of those other components could be leaking a little voltage onto that wire. It may be a "phantom" voltage, not even able drive enough current to bother anything at all. I wouldn't worry about it.

If you're an electronics type, and had, say, a 1K resistor, you could connect it to the phantom side of the fuse socket and to ground (without the fuse), and then check it — the voltage would probably disappear, even with that light load (12 mA).
Click to expand...

Far more likely is that a 20 year old air hose is split. This was already very common 10 years ago when I had to figure out why lockers didn't work.
 
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jjvw said:
Far more likely is that a 20 year old air hose is split. This was already very common 10 years ago when I had to figure out why lockers didn't work.
Click to expand...

I agree. I was just answering his other question about the odd voltage on the fuse output side.
 
Good thread, I am suspecting a leak in mine. The lights come on, blink, go solid, then blink again, sometimes front, sometime rear, then sometimes they stay solid. Thinking there may be a leak somewhere. I will say even when the light is blinking it seems / feels like the front locker is engaged.
 
Danarch said:
... I will say even when the light is blinking it seems / feels like the front locker is engaged.
Click to expand...

If the experience is a loss of steering and the the Jeep trying to push straight, that is because the rear is locked and the rear axle lost differential action. The front alone being locked does not do that.
 
jjvw said:
If the experience is a loss of steering and the the Jeep trying to push straight, that is because the rear is locked and the rear axle lost differential action. The front alone being locked does not do that.
Click to expand...

It is more difficult to steer, but does steer. It feels about the same as my JK with the lockers when it happens. I admit i am not sure I understand “lost of differential action” my brain wants to Interpret that as the read axle isn’t working, but I know its working. Do you mean that it has lost the ability for each axle to rotate independently since they are locked?
 
Danarch said:
It is more difficult to steer, but does steer. It feels about the same as my JK with the lockers when it happens. I admit i am not sure I understand “lost of differential action” my brain wants to Interpret that as the read axle isn’t working, but I know its working. Do you mean that it has lost the ability for each axle to rotate independently since they are locked?
Click to expand...

Think about what differentials do, what lockers do, and what happens when steering is introduced to either.

A locked only rear will resist steering because the differential no longer allows differential action between wheels. The Jeep will fight hard to only go straight, regardless of the steering.

A locked only front will still be able to steer because the wheels point that direction and the rear axle will allow differential action between the wheels.

A locked only front will feel stiff at the steering wheel, but the actual ability to steer the Jeep is very minimally affected. Add in hydro assist to the steering and the stiffness is barely perceivable.
 
OldBuzzard said:
Per the FSM, that fuse feeds several things, not just the locker stuff. Any of those other components could be leaking a little voltage onto that wire. It may be a "phantom" voltage, not even able drive enough current to bother anything at all. I wouldn't worry about it.

If you're an electronics type, and had, say, a 1K resistor, you could connect it to the phantom side of the fuse socket and to ground (without the fuse), and then check it — the voltage would probably disappear, even with that light load (12 mA).
Click to expand...

thanls. Since it is working again, I'm happy to wait it out and see. I just hope the harness doesn't fry at an inopportune time! :LOL:
 
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