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Shift issues

C

catpower

NAXJA Forum User
Location
Kansas City, MO
I have a 98 with the automatic. If I am in drive, and start from a stop it will not shift down to 1st gear. If I pull the shifter down to 1-2 it will go in just fine. Now, for the other side of this, I have to push the shifter forward to engauge the neutral safety switch to get it to start. Could my shifting issue be related to the linkage needing adjustment, or am I looking at a tcm or solenoid? Fwiw, the check engine light is on, but I haven't hooked up to scan for codes yet.
 
1. PULL the codes. They yield valuable clues as to what might be wrong.

2. My guess is that this could be caused by a faulty "throttle position sensor". This sensor is directly involved with the shifting characteristics of the AW4 electronically controlled transmission.
 
Ok, my codes are P0758D (Shift solenoid B) and P0705 (Neutral safety switch). The second code makes sense to me because it's obviously out of adjustment. Now, what to do about the P0758D?
 
the neutral safety switch is going bad, replace it. the 98 and up XJs use input from the NSS to tell the pcm what gear the vehicle is in since the trans computer is built into the main PCM, not seperate like the older models. I would replace it, clear the codes, and see if the other one comes back.
 
Drop the pan, and disconnect the solenoid, and test it with an ohm meter. Should be about 14 ohm as I recall. Also can test it with a 12 volt battery, to see if it opens and closes. Simple electric valve. If the solenoid is good, you get track gremlin wiring, :banghead:LOL!!
 
GrimmJeeper said:
the neutral safety switch is going bad, replace it. the 98 and up XJs use input from the NSS to tell the pcm what gear the vehicle is in since the trans computer is built into the main PCM, not seperate like the older models. I would replace it, clear the codes, and see if the other one comes back.
Click to expand...

What year did the PCM and TCU merge?
 
I believe it was 98. I know a 97- trans will not work in a 98+ xj because of the wiring for the trans, I am assuming that is when the two units merged.
 
GrimmJeeper said:
the neutral safety switch is going bad, replace it. the 98 and up XJs use input from the NSS to tell the pcm what gear the vehicle is in since the trans computer is built into the main PCM, not seperate like the older models. I would replace it, clear the codes, and see if the other one comes back.
Click to expand...

Will do, off to Oreilly's I go. I will let you guys know if I'm fixed!
 
Heh, funny :D Well, I found out pretty quick how expensive these damn things are! And I found out the plastic part of the switch was broken. This caused a lot of crud build up, and made those copper brushes stick down. I found a switch on fleabay for $50, so I think Ill take my chances on it and see what happens!
 
Well, switch came in today, quick simple install. Got it adjusted out, my back up lights work now, starts in neutral and part ok. Cleared my faults and started it, they didn't come back immediately like they did before. I have to wait to test drive it. I found the right side wheel bearings were shot, so Im waiting for a new timken hub to show up, and my hd steering linkage because the stock stuff is taco'd. Getting ever so closer to being able to take a test trail run!
 
Finally got it together for a test run tonight. Still shifts the same way and my faults came back. But, it still starts ok in park and neutral, and the reverse lights are functional. So I know the TRS sensor is adjusted right. What gives?
 
The bit about the tcu merging is false, sorry. I am holding a 98 TCU right now. They moved them from the pass side of the dash to the driver side.

The only XJs with a PCM instead of seperate ECU and TCU are the 2.5L autos and possibly the very early models with V6s and autos, I don't know anything about those.

The TCU breakdowns are (all for 4.0L)
87-90 renix, 1pulse/rev oss, old style tps signal, old style nss, old connector
91-96 obd1, 1pulse/rev oss, new style tps signal, old style nss, newer connector? And 96 may be slightly smarter but not by much. 96 is obd2 but seems the same tcu wise.
97 obd2, 1pulse/rev oss, new style tps signal, new style nss, 97+ connector
98-01 obd2, 4pulse/rev oss, 16?pulse/rev iss, new style tps signal, new style nss, 97+ connector

May be some updates within each range but they are all hw and firmware upgrades and should plug and play.
 
Last edited:
OSS and ISS are?
 
GrimmJeeper said:
I believe it was 98. I know a 97- trans will not work in a 98+ xj because of the wiring for the trans, I am assuming that is when the two units merged.
Click to expand...

kastein said:
The bit about the tcu merging is false, sorry. I am holding a 98 TCU right now. They moved them from the pass side of the dash to the driver side.
Click to expand...

I was going to say, this is the second time I saw you post that, and I know for sure that '99 still had a TCU, and my dad's '01 has one. Hadn't heard that they merged them until yesterday. Made me question the '00 and '01.
 
I have not checked the TPS, I read about that earlier, Im going to do a sweep on it with my dvom and see what it's doing. I worded my search a little different on the boards and google and finally came up with some different results and a couple guys that had the same issue. Looked like one had a TPS issue and the other had a ground issue between the TCM and Tranny. I looked at All Data diy today, but it looks like their info is about worthless.
 
Ecomike said:
OSS and ISS are?
Click to expand...
output speed sensor and input speed sensor. The 98-01 setup also changes from the earlier reed switch variety to a design more similar to the ABS sensors and RENIX CPS, though the magnet is on the rotor rather than being attached to one end of the inductor core.
 
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