lazyxj
NAXJA Member #1310
- Location
- Los Angeles
Like a lot of XJ owners with an AW4 transmission, I want to be able to lock it in 2nd gear at times. The unintended downshifting into 1st can be annoying and sometimes downright dangerous on loose downhill grades.
After searching and reading everything I could on
and Go-Jeep’s sites, I tried to wire my 2001 so that I could lock it when the shift selector was in the 1-2 position.
I first found the two wires coming from the TCU that control the shift solenoids. I connected two digital voltmeters to the wires to observe the powering up and down of the solenoids. Everything worked as it should. I cut the wire to the second gear solenoid and, using jumpers, connected a diode, as suggested by Go Jeep into the circuit. I then put the trans into 1-2 and powered up the solenoid. It locked second gear as promised. The ‘check engine’ light came on, as expected. I hooked and un-hooked the power several times and the trans went into 1st and 2nd as expected. I then tried Drive. The trans would shift directly from 1st into 3rd, bypassing 2nd. Now I was wondering if I had blown the TCU. I connected my OBDII scanner and sure enough, it reported a bad shift solenoid circuit. When I cleared the fault, the trans resumed normal shifting.
I tried wiring the lockout with and without the diode, both ways having the same result, The lockout works but as soon as the ‘check engine’ light comes on, it will not shift normally in Drive. Second gear will always be bypassed.
So is there a solution or is this how the 2001 XJs are programmed?
I could get a manual system, like Brett’s, but since I drive 20,000+ miles a years on LA’s congested freeways, there is no way I want manually shifting all the time. All I want is a 2nd gear lock for the few times it’s really needed.
After searching and reading everything I could on
and Go-Jeep’s sites, I tried to wire my 2001 so that I could lock it when the shift selector was in the 1-2 position.I first found the two wires coming from the TCU that control the shift solenoids. I connected two digital voltmeters to the wires to observe the powering up and down of the solenoids. Everything worked as it should. I cut the wire to the second gear solenoid and, using jumpers, connected a diode, as suggested by Go Jeep into the circuit. I then put the trans into 1-2 and powered up the solenoid. It locked second gear as promised. The ‘check engine’ light came on, as expected. I hooked and un-hooked the power several times and the trans went into 1st and 2nd as expected. I then tried Drive. The trans would shift directly from 1st into 3rd, bypassing 2nd. Now I was wondering if I had blown the TCU. I connected my OBDII scanner and sure enough, it reported a bad shift solenoid circuit. When I cleared the fault, the trans resumed normal shifting.
I tried wiring the lockout with and without the diode, both ways having the same result, The lockout works but as soon as the ‘check engine’ light comes on, it will not shift normally in Drive. Second gear will always be bypassed.
So is there a solution or is this how the 2001 XJs are programmed?
I could get a manual system, like Brett’s, but since I drive 20,000+ miles a years on LA’s congested freeways, there is no way I want manually shifting all the time. All I want is a 2nd gear lock for the few times it’s really needed.
