fixbroke
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Some of us are now painfully aware that the locker sensors in the new Advantek 44 Rubicon axles are prone to failure. Even more annoyingly, the sensors are not available to purchase outside of a complete new axle assembly. You cannot buy this sensor if/when it fails.
The main failure cause seems to be that gear oil gets into the sensor housing and shorts the PCB with the fine metal particles suspended in the oil. It happens most often on long highway trips on the rear diff, where there is a lot of heat being generated in the gear oil, which in turn thins the oil to the point that it can get past the sketchy seals of the sensor housing.
This will first result in a flashing locker light telling you the axle is in the process of unlocking, even though it's not locked. Lockers will still work for a while, but eventually the flashing light will be replaced by a solid warning with the message "service axle locker system" and the lockers will no longer engage. If your sensor has gotten to this point, it's too late to save it. You can try to get Jeep to warranty the entire axle, but if you've changed your gearing then they will refuse to warranty due to the modifications. Your only option is to buy a Z Locker OEM to bypass the sensor in the affected axle.
This guide explains how to remove your working sensor and fill it with silicone (aka "potting", a common procedure to protect electronic components) to oil-proof the important bits. Note that if you still have stock gearing, this will void your sensor warranty so you may want to wait till the end of your warranty period before doing this. If you've re-geared, I can't recommend enough that you do this before your sensors fail since you don't have warranty protection anyway and you can't buy a replacement sensor. I've been running mine like this for around 1000 miles now and it has been working well.
1. Drain your differential and remove the cover.
2. Remove the locker sensor torx screw. An L-handle torx wrench works well since there's not a lot of clearance from the bearing cap bolt.
3. Remove the sensor. You may need to push the locker ring towards the ring gear to get enough clearance to free the sensor. At this point it's not a bad idea to clean the metal shavings from the magnet that was hidden under the sensor.
4. Disconnect the wiring connector by sliding the red tab back, then pressing on it while you wiggle the connector free.
5. Drill a small hole in the white plastic cap. You can use a much smaller bit than what's pictured, or better yet use a small rotary tool. BE VERY CAREFUL that the drill doesn't pull itself into the PCB inside. Go very slowly, or use a rotary tool that won't pull itself into the hole. Remember that these sensors are unobtainium and you're gonna feel really bad if you break it!
6. Drill another small hole in the pocket on the other side of the sensor. Again, BE VERY CAREFUL not to damage the PCB inside.
7. Use a small tube of RTV silicone to push silicone through the bottom hole until it completely fills the sensor and exits the top hole. I used red high-temp RTV since I had it on hand, but any kind will do so long as it's not electrically conductive. Do not use the copper stuff!
8. Allow the silicone to cure, then trim off any excess with a knife.
9. As an additional precaution, I filled my connector with dielectric grease since I suspect that is a major path for oil to enter the housing. EDIT: there's some contention as to whether dielectric grease is suitable for sealing connectors. You may wish to skip this step, but if you're feeling curious then read on in this thread for a discussion of its intended use.
10. Reinstall the sensor. I recommend using some blue threadlocker on the torx screw.
11. Reinstall the diff cover and refill your diff oil. You're done! Your sensor should now be potted and oil-proofed.
The main failure cause seems to be that gear oil gets into the sensor housing and shorts the PCB with the fine metal particles suspended in the oil. It happens most often on long highway trips on the rear diff, where there is a lot of heat being generated in the gear oil, which in turn thins the oil to the point that it can get past the sketchy seals of the sensor housing.
This will first result in a flashing locker light telling you the axle is in the process of unlocking, even though it's not locked. Lockers will still work for a while, but eventually the flashing light will be replaced by a solid warning with the message "service axle locker system" and the lockers will no longer engage. If your sensor has gotten to this point, it's too late to save it. You can try to get Jeep to warranty the entire axle, but if you've changed your gearing then they will refuse to warranty due to the modifications. Your only option is to buy a Z Locker OEM to bypass the sensor in the affected axle.
This guide explains how to remove your working sensor and fill it with silicone (aka "potting", a common procedure to protect electronic components) to oil-proof the important bits. Note that if you still have stock gearing, this will void your sensor warranty so you may want to wait till the end of your warranty period before doing this. If you've re-geared, I can't recommend enough that you do this before your sensors fail since you don't have warranty protection anyway and you can't buy a replacement sensor. I've been running mine like this for around 1000 miles now and it has been working well.
1. Drain your differential and remove the cover.
2. Remove the locker sensor torx screw. An L-handle torx wrench works well since there's not a lot of clearance from the bearing cap bolt.
3. Remove the sensor. You may need to push the locker ring towards the ring gear to get enough clearance to free the sensor. At this point it's not a bad idea to clean the metal shavings from the magnet that was hidden under the sensor.
4. Disconnect the wiring connector by sliding the red tab back, then pressing on it while you wiggle the connector free.
5. Drill a small hole in the white plastic cap. You can use a much smaller bit than what's pictured, or better yet use a small rotary tool. BE VERY CAREFUL that the drill doesn't pull itself into the PCB inside. Go very slowly, or use a rotary tool that won't pull itself into the hole. Remember that these sensors are unobtainium and you're gonna feel really bad if you break it!
6. Drill another small hole in the pocket on the other side of the sensor. Again, BE VERY CAREFUL not to damage the PCB inside.
7. Use a small tube of RTV silicone to push silicone through the bottom hole until it completely fills the sensor and exits the top hole. I used red high-temp RTV since I had it on hand, but any kind will do so long as it's not electrically conductive. Do not use the copper stuff!
8. Allow the silicone to cure, then trim off any excess with a knife.
9. As an additional precaution, I filled my connector with dielectric grease since I suspect that is a major path for oil to enter the housing. EDIT: there's some contention as to whether dielectric grease is suitable for sealing connectors. You may wish to skip this step, but if you're feeling curious then read on in this thread for a discussion of its intended use.
10. Reinstall the sensor. I recommend using some blue threadlocker on the torx screw.
11. Reinstall the diff cover and refill your diff oil. You're done! Your sensor should now be potted and oil-proofed.
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