DisorganizedMan

What's up guys,

I posted a little while back about a new-to-me '98 XJ I bought about a month ago...I immediately took it to a mechanic because it was throwing a code for a transmission issue (P1745). I ended up driving it back home from the mechanic after he thought it was safe to drive home. We both figured it was an intermittent thing. I have not noted any really hard shifting or anything while driving it, and neither did he, whether the Jeep was running cold or at operating temperature.

Anyway, I swapped out the solenoids yesterday and did a filter change / poor man's flush while I was at it. Unfortunately, after I was done: turn the Jeep on, let it warm up, take it for a spin, and while it's shifting like butter, it is still throwing a transmission code. With my cheap OBDII reader it's saying P0753, which is supposed to be Shift Solenoid A.

Could there be any other reasons for this? This is my first auto transmission car, but from what I can tell it shifts just fine through all the gears. If I clear the code it immediately comes right back on.

Trying to figure out what to do next, as I'd like to get this thing in prime condition and ready to roll for the fall!

Thanks in advance!

fordraceboy

"From what I can tell..."


Does it shift early into 2nd, or not kick down into 1st when you stab the throttle right after it goes into second?

DisorganizedMan

Alright so I took it for another drive to really run it through the ringer and see. Honestly, I don't really feel anything blaringly wrong...

-if I drive it as though I'm commuting to work, it will shift from 1st to second around 2k rpms. It seems to like to sit between 1500-2000 rpms and will shift no later than 2500 around.

-if i drive it like I'm here to party, it seems to respond pretty well. If I slam on the gas immediately from stop, it will jump up maybe to 3k rpms and then shift right into second, and then if I floor the pedal again it seems to jump right back into first, and once I get up to speed shift right back into 2nd, or 3rd, or wherever it's happy.

Now when I drive hard, its not THE smoothest shifting ever, definitely jumps a little bit like it's surprised, but nothing that I would consider overtly "bad." Once again this is my first auto transmission so I'm not sure if I'm just missing something here, but honestly it seems to be doing a good job.

I just checked the harnesses in the front and none of the wiring seems to be frayed or screwy. Going to get under the Jeep again and look at the wiring going to the transmission.

FWIW I cleared the codes again and they immediately came back on...

DisorganizedMan

OK so I just got under the Jeep. From what I can tell the wiring looks alright. The NSS and its associated wires seem to be in good condition, and the wires going to the solenoids seem good too. They are mostly covered in wire sleeves, but for the plugs and everything they look good.

Under the hood, the grey plug is clean as a button and all the pins are clean and connections look good. Same for the black plug. There IS a bigger black plug that I am having a little trouble getting apart, but it looks like the wires going into it are good. Is this plug associated with the transmission as well?

Where else can I get into to check connections? Is the TCU located under the hood?

Unfortunately I don't have an ohmmeter but I'm considering going out to buy one soon by the way things are looking!

fb97xj1

The TCU, or TCM, is under the driver side of the dash, to the right of the gas pedal.

DisorganizedMan

awesome thank you!

I have to get a voltage meter and start checking things. I plugs and connections are all looking great mysteriously.

DisorganizedMan

alright,

I unplugged the TCU and everything looks squeaky clean there. At this point, even if I did check the wiring and found something wrong, is that an easy fix to do on your own?

I bought the thing with hopes in learning more about how cars work and fixing it up myself, but I'm kinda just ready to bring it to a trusted mechanic...I'm not sure I have the ability to put in all new wiring...

DisorganizedMan

I want to add that if I clear the code, the check engine light comes on within 10-20 seconds. It does not matter whether the car is running or if the key is just in the ignition. Would I be correct in thinking that it's an electrical issue because of this?

DisorganizedMan

Alright. I was just looking at the AW4 factory manual and saw this: "once a malfunction is noted and stored in the TCU memory, it is retained even after the problem has been corrected. To cancel a stored malfunction, simply disconnect the "trans" fuse in the TCU harness."
am i missing something here? is there a trans fuse somewhere near the TCU that I can try to disconnect?
I'm working night shift through the weekend and so probably wont be using a multimeter until mon or tues!

DisorganizedMan

alright, just got a multimeter. How do I check for continuity / resistance within the relay? the how-to on line is saying to hook one end up to the solenoid plug and another to the battery terminal, but my multimeter wires will definitely not stretch that far...am i missing something?

DisorganizedMan

aha! I just saw that CAV24 is my ground....i was never the best at reading directions i suppose.

DisorganizedMan

alright still having trouble...the multimeter I got is from NAPA, and the cables that come with it have pointed ends that don't really fit into the TCM plug. I tried to use safety pins but it's really hard to get them to stay on the cables with the pointed ends. Also, which side of the TCM am i supposed to be testing? the part that plugs in or the TCM itself? Either way it was pretty difficult to get to there. I ended up not getting a reading