jeepin4fun

So I just bought this 96 xj about a month ago. I noticed the other day that when I turn the key to the on position the check engine light doesn't come on. So I hooked up the obd reader and pulled the p1698 and p0441.

p0441 looks like the gas cap was just loose so I cleared it.

p1698 looks like I need to check the tcm which i believe is under the dash on the passenger side. And in 97 they put it under the driver side dash. The thing drives fine and shifts good. While looking around I found a plug above the transmission that is just hanging there not plugged in but I couldn't find where it goes. I can take a picture if it helps.

I checked the fuses and nothing is blown (next to the battery and brake pedal). I also check the computer next to the air filter (i believe it is the ecm) and looks fine.

Any help would be great thanks!

DFlintstone

I'm no real help. I guess that's an issue with the PCM & TCU communicating. Sounds like a pain and a long-shot but you might check the connections on both. Then maybe leave the battery disconnected overnight....Idk.

I did find this, there is mention of a buliten...http://www.jeepsunlimited.com/forums...d.php?t=462082

Since wiring harnesses are made to accommodate a bunch of configurations, it's not unusual to find plugs/loose ends that don't go to anything you have.

I'd clean all the connectors I could find. Aren't there some to the trans there behind the dipstick? Might as well clean the connector to the TPS since it has trans wires.

Also just on GP you might want to clean the ground there by the dipstick. May be the TCU , PCM and other stuff grounds there. Again a pain and a longshot, but wiring connections and grounds are always on the list.

Hey! I went to Thurston in Laguna Beach Btw. Both the tap-water and the "big water" are "memorable".

KD4315

Checking TCM on CCD Bus:

Use a digital volt/ohmmeter....

Disconnect and isolate negative battery cable from battery,

Refer to the schematic above,

Detach connector from the TCM,

Refer to the TCM pin out drawing below (view looking at the detached TCM connector),



Using your digital ohmmeter, measure for continuity (near 0 resistance) between pin 6 of the TCM connector and pin 11 of the Data Link Connector (DLC), Check for resistance between pin 7 of the TCM connector and pin 3 of the DLC. Any high resistance or open indicates the TCM may not be connected to the CCD Bus.

The same process can be used to check the SCI Transmit TCM wire. Measure for continuity beteen pin 14 of the TCM connector and pin 7 of the DLC. An open or high resistance reading may indicate the TCM SCI signal is not connected to the DLC (scanner).

While you're here, using your digital ohmmeter, measure for continuity beteen pin 24 of the TCM connector (TCM ground to ground point G101 on engine) and a good chassis ground (gas pedal pivot bracket mount bolt is good).

~~~~~~

Attach TCM connector,

Attach negative battery connector.

~~~~~~

Using your digital voltmeter....

Turn ignition switch to Run (engine off),

Touch positive probe of voltmeter to pin 3 of the DLC and negative probe of the voltmeter to pin 4 of the DLC. You should read about 4.5 volts. Touch the positive probe to pin 11 of the DLC and the negative probe to pin 4 of the DLC. You should read about 4.5 volts.

Voltage readings significantly out of range of the 4.5 volts may indicate a module on the CCD bus is corrupting the bus.

jeepin4fun

Thank for the replies.

So I'm going to pull the tcm out and check it against your list and see if its bad.

The reason that I started checking on this was that the check engine light never comes on. When you first turn the key and it is supposed to come on and test it doesn't. So I was thinking it may be an issue with the ecm? But Im going to look behind the dash and see if there is any bad connections.

Ill be back with some info........wish me luck.

jeepin4fun

kd4315

I pulled the tcm out and it has 16 rows. I believe that pin out is for 97+. Would you happen to have it for the older tcm?

So I pulled the battery and let it sit for awhile. Checked the ecm tcm all looked good. Pulled the hole dash apart couldn't find anything loose around the cel light. I think the bulb is bad for the cel so I need to figure out how to replace it. When I hooked everything back up and pulled the codes it still says the p1698 and it says the mil is on. So the cel should be lit.

Should I just replace the tcm and see if that is my problem? I read that when it goes bad usually the trans doesn't shift on its own and you have to manually shift it. Drives fine so not sure what I should do next. Any ideas?