RoyL

98 Cherokee Sport, 4.0 Engine, Auto Trans, 4x4

Background: recent purchase, no CEL displayed… tried the “trick” dash check with odometer button and key, which did not show any codes. I discovered I don’t see the “check engine” light on the gauge cluster, so gonna check the bulb. I have a “CarChip” ODBII reader, but it wouldn’t read any codes either. I’m gonna create a separate thread on this apparent ODBII communication issue. I had the ODBII scanned at AutoZone and they were successful and downloaded these:

P0700 – AutoZone description: Transaxle control system fault, ECM received a signal that the transaxle control module has a fault, probable cause: 1. Shorted or open circuit within transaxle, 2. Failure of transaxle control module. I have read that this is a general trans control code, then you’ll also get more specific ones, i.e. P0705/P0743 below?

P0705 – AutoZone description: Transmission range sensor out of position. ECM has detected the transmission range sensor was out of position. Probable cause: defective transmission range sensor, 2. Open or shorted circuit condition.
This website description: couldn’t find this one… I have symptoms related to this one… Occasional no start (happened once) and reverse lights sometimes work, sometimes not. NSS=Trans Range Sensor, right?

P0743 – AutoZone description: Torque converter clutch solenoid circuit condition. PCM detected an open or short condition on the solenoid circuit. Probable cause: 1. Open or short condition on the solenoid circuit
This website description:
P0743 (M) Torque Converter Clutch Solenoid/ Trans Relay Circuits An open or shorted condition detected in the torque convertor clutch (part throttle unlock) solenoid control circuit. Shift solenoid C electrical fault - Asin transmission I believe this is the trans I have?

I haven’t noticed any significant issues related to overdrive lock-up, although, it does kinda go in and out of lock-up at 50ish MPH with slight throttle movements, but not harsh. Gonna pay more attention to speeds and lock-up now to see if it’s consistent. Just yesterday, another member had this P0743 code, and CCKen posted a troubleshooting procedure for the TCM which I’ll try: https://www.cherokeeforum.com/f2/cod...4/#post2796828

Can these 2 codes [P0705 and P0743] both be related to trans selector position detecting out of position faults?

freegdr

Get bulb replaced its wired in conjuction with ecm .Then scan again.

RoyL

Thx! That's 1st priority on the list then. Just posted another thread on ODB/CCD voltages, could be related?

CCKen

I replied to that thread. I'm waiting to see how that turns out before continuing on this thread.

XJwonders

Yes the range sensor is the NSS.

freegdr

Ever dawn on ya those codes all have to do with movement of vechicle . Were you driving when tranny codes were scaned ?

RoyL

Thx, making sure of the terminology used.

?trick question? Yesterday, I swapped the check gauges bulb to the CEL bulb slot, since CEL bulb is missing. Then drove to AutoZone to re-scan. Got P0700 and P0138 [known O2 disconnected].

Today, troubleshot the CCD voltage, disconnected and reconnected the TCM, disconnected the battery in there as well. Started it up and drove it a bit, CEL light was not on initially, but came on after about 20 minutes. Stopped in AutoZone and scanned, only P0138 now...

Still have the CCD voltage issue, but for now... no trans codes. Gonna get the missing bulb replaced in the cluster so all are there and keep monitoring the CELs. Will likely take the NSS apart for a cleaning/adjusting sometime soon. Thx for the tips, wealth of knowledge on this forum!
Roy

CCKen

If you have no real problems with transmission shifting and the P07XX Codes have gone away (for now) I don't see a need to clean the TRS/NSS. Besides, you can check the TRS/NSS from the TCM connector.

Be aware that there may be DTC's 'pending' that the Idiotzone clerk did look for.

RoyL

Prev Owner said shifter had caused him a no start situation on occasion, he had to wiggle the shifter to get it to start. Where are troubleshooting procedures to check the NSS at the TCM? Definitely would like to check it, before i undertake pulling it off.

CCKen

This is a voltage check of the Transmission Range Sensor (NSS) from the TCM connector. Power comes from fuse F10 in the JB.

You will need a digital voltmeter. Set to 20 VDC scale.

Review the wiring diagram and the TCM connector pinout below.

When doing the voltage checks you need to place the trans gear selector in each of the gear ranges being tested, and have the ignition switch in the RUN position. You will also be cross checking to different TCM pins/gear selections while in a selected ger to see if there is a voltage cross bleed. You will be using TCM connector pin cavity 24 as the ground for your meter (-) probe.

You cannot check the P/N (Start) function of the TRS from the TCM connector.

1. Select Park then Neutral and check pin cavities 9, 18, 21, and 22 for voltage at each selection. You should see none.

2. Select R (Reverse) and check from pin cav 18 to ground.

3. Select D (Drive) - pin cav 22 to ground.

4. Select 3 (3rd gear) - pin cav 9 to ground.

5. Select 1-2 (gears 1 and 2) - pin cav 21 to ground.

Each selection/pin cav should show battery voltage and no cross bleed voltage. Wiggle the gear selector to see if the voltage reading change.

RoyL

Thanks much, Ken! This is on my list when I get some time.

RoyL

Well, the Transmission code P0743 has come back. I cleared it after all the troubleshooting on the OBDII CCD circuit, involved disconnecting the TCM. But it came back. I have no OD lock-up symptoms, it shifts thru the gears fine and locks up on the highway, so why a P0743? I did have a cracked flexplate that I replaced, started making an awful racket, just like some have described here on this forum... It does have a "shudder" type vibration on take off from a stop, can feel it thru the steering wheel as well as the seat. Seems to go away once rolling past 15 MPH.

CCKen

Odd...

The '99 FSM and the 2000 FSM, Section 25, lists P0743 twice, reading like this:

P0743 (M) -Torque Converter Clutch Solenoid/ Trans Relay Circuits - An open or shorted condition detected in the torque converter clutch (part throttle unlock) solenoid control circuit. Shift solenoid C electrical fault - Aisin transmission

P0743 (M) - Torque Converter Clutch Solenoid/ Trans Relay Circuits - An open or shorted condition detected in the torque converter part throttle unlock solenoid control circuit (3 or 4-speed auto. trans. only).

Note that the last one says 3 or 4 speed auto transmissions

The '97 FSM lists P0743 with similar wording as the '99 FSM, but says it's for a 3 speed transmission only.

The 2001 XJ Diagnostics Manual doesn't list P0743 at all.

I don't have the '99 Transmission Diagnostics Manual (only the Body and Powertrain manuals) so I can't look up the diagnostics procedures for P0743.

You do have a 1998 XJ, with an AW4 transmission don't you?

Try reading the stored codes again usng a different scanner, or scanners.

~~~~~~

I'm wondering if that "Shudder" you feel isn't the torque converter clutch talking to you.

RoyL

Update. Consistently get the P0743 now. I reset the CEL and drove it for about 15 minutes and the CEL came on, and after that, I'm fairly certain it wasn't locking up... So, I checked the solenoids resistance from the TCM, pin cavs 11, 12, 13 to pin cav 24 (ground) and solenoid C, pin cav #11, initially showed 36 ohms cold and then 'open' (no connection) after a long drive. So definitely looks like solenoid problem.

The other 2 solenoids checked out at about 18-19 ohms. I've seen that 11-15 ohms is within spec. If I replaced all 3, anything else I need to check while I've got the pan off?
Thx.
Roy

CCKen

When you get the pan down double check the resistance of all three solenoids while still installed (see pic) to verify the solenoid(s) are, in fact, having out of spec readings. If they are out of spec (11-15 Ohms) when doing this, suspect that there's resistance in the wiring from the TCM to the solenoids. A weak spot is the connector(s) at the trans dipstick tube (see pic). You would want to seperate the connector(s) and inspect the pins for corrosion, and clean them out with electronic cleaner before reassembly.

If the two solenoids are still reading 18-19 Ohms, suspect a cheap Ohmmeter.

Solenoids: