[Swagger_Wagon]

Jeep started a little slower than expected today, but nothing alarming. It was it's first below freezing start of the season. Anyways,I get a "check gauges light". Oil pressure fine, tach fine, voltage meter... pegged all the way to the left at 9. Shortly after the CEL came on. I drove around to see if it was still running OK.

Jeep was driving perfectly so I took it to Auto Zone right away to get the codes pulled. It was P1698. Guy said it was probably my alternator, which made sense because of what was going on.

Get home and google it though and find that it's related to the TCM, PCM, and all this other stuff. And what is this "NO BUS" crap I keep reading about?

Thanks!

Am also reading it has something to do with the tranny... what in the hell?

[kadetklapp]

I found this about it-

your code is a communication loss code between the TCM and the other module(s). It's not uncommon for the wiring problems to develop in the harness that runs from the PCM in frt of the battery to the TCM

Start by getting the battery and alternator tested. If that's all good start checking wiring. How's it shifting? Does it seem to be in limp-mode?

FYI, I had a battery go bad on my old 99 XJ. I started it, started driving home, and the lights dimmed out, cluster quit, and the Jeep wouldn't shift correctly. Thought it was alternator and a trans problem. Turned out to be a battery with dead cells in it.

[Swagger_Wagon]

Tranny shifted great! No issues at all. Was running as strong as usual. Battery is less than a year old... but worth a shot to load test it. And for all I know the alternator could be original to the Jeep, so that could be the culprit.

[dukie564]

betting on crappy battery contacts / corrosion, or a crappy ground on this one.

Clean up the battery terminals really well, and clean up both the engine (behind the valve cover) and the battery ground connections.

[CJ7-Tim]

P1698 No CCD/J1850 Message From TCM. No CCD/J1850 messages received from the electronic transmission control module (EATX) or the Aisin transmission controller.
P1698 No CCD Messages Received From PCM. Bus communication failure to PCM. A "Companion DTC" was set in both the ECM and PCM.


Bus Failure or a No Bus indicated on the odometer points a failure of one of the 5 volt sensors, or a short/open circuit. Start by checking the fuses under the hood and in the fuse box. Inspect the wire harness for obvious damage from melted or chafed insulation or pinched wires. Be sure to carefully inspect any previous work and the wires/wire harness to the NSS. Inspect the wires to the Crankshaft Position Sensor (CPS) and test the CPS. Clean and adjust the Neutral Safety Switch, test the Throttle Position Sensor.


P 1698 Possible Causes
CCD Bus (-) circuit open between PCM and TCM.
CCD Bus (+) circuit open between PCM and TCM.
Transmission CCD bus wiring damaged.
Faulty TCM.

Diagnostic Procedure
1. Using scan tool, clear TCM DTCs. Start engine and let idle for at least 2 minutes. Using scan tool, retrieve TCM DTCs. If DTC P1694 returns, go to next step. If DTC P1694 does not return, go to step 5.

2. Check instrument cluster gauges for proper operation. If fuel gauge and speedometer operate properly, go to next step. If fuel gauge and speedometer do not operate properly, see appropriate INSTRUMENT PANELS article.

3. Turn ignition off. Disconnect Gray PCM harness connector. PCM is located at left front of engine compartment. Disconnect TCM harness connector. Measure resistance of CCD BUS (-) circuit (White/Black wire) between TCM harness connector and Gray PCM harness connector. If resistance is more than 5 ohms, repair open in CCd BUS (-) circuit (White/Black wire). If resistance is 5 ohms or less, go to next step.

4. Measure resistance of CCD BUS (+) circuit (Violet/Brown wire) between TCM harness connector and Gray PCM harness connector. If resistance is more than 5 ohms, repair open in CCd BUS (+) circuit (Violet/Brown wire). If resistance is 5 ohms or less, replace TCM.

5. Conditions necessary to set DTC P1694 are currently not present. Inspect related wiring and harness connectors. See WIRING DIAGRAMS. Repair as necessary. If no problem is found, check for broken, bent, backed-out or corroded terminal pins. Check for chafed, pierced or partially broken wires inside insulation. Repair as necessary. 4. Measure resistance of CCD BUS (+) circuit (Violet/Brown wire) between TCM harness connector and Gray PCM harness connector. If resistance is more than 5 ohms, repair open in CCd BUS (+) circuit (Violet/Brown wire). If resistance is 5 ohms or less, replace TCM.

[Swagger_Wagon]

CEL went off

****in' Jeeps

[99Greenmachine]

Originally Posted by Swagger_Wagon

CEL went off

****in' Jeeps

always seem to happen haha.

Was there a slow start on the run which yielded the CEL light?