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P1694 Troubleshooting

carguy007

NAXJA Forum User
Location
Central TX
2001 XJ, 4.0L auto. This is my son’s XJ, daily driver to/from school

3 weeks ago replaced 2 top O2 sensors, NTK Brand . (hindsight should've done all 4 at once), not sure if this relevant.

A week later CEL comes on - P1694, my son said gauges would go to zero and engine would briefly cut off for a second, but would keep running. It would do this every couple of minutes. Towed it home

Checked & cleaned all grounds, bought a new battery (old one tested bad), cleaned terminals on back of cluster. cleared code and all was good for another week.

Week later - same issue – this time would not fire and had “no bus” on odometer. It sat overnight, and fired the next morning, but same symptoms. When I fired it that morning, I checked and picked up 2 additional codes: P0130 & P0136. I went ahead and replaced the lower O2 sensors (NTK).

The crank sensor and cam sensors were replaced 6 months ago. Rechecked crank sensor with ohm meter – good.

Here is the issue:
Checked voltage on DLC - reading .32 volts on pin 3, and .09 volts on pins 11, ground to pins 4/5. This voltage did not change by removing Crank, Cam, TPS and Map sensors. The pin 3 reading went to .13 volts when I disconnected TCM.
Checked resistance on DLC pin 3 and pin 11 = 60 ohms (should be 120)

Checked resistance on harness both CCD+ and CCD- between PCM and TCM – 0 ohms good
Checked voltage from PCM on both orange and purple wires, both 5v – good

This leads me to believe it’s the TCM. Is there a way to test the TCM? I believe it was shifting fine previously.

Is there anything else to check?

Lastly, if you can provide a link for a FSM download, that would be great. Most of those sites redirect everywhere.

Thanks in advance.
 
Try www.pacificcoastmanuals.com


TCM failure is not very common, but they also are not very expensive at the junkyard.

I would suspect any OBD sensors that are not genuine Jeep parts, and would inspect any recent repairs or modifications for wire harness issues or wire plug issues. Look for chafed or melted wire insulation, cut wires from sharp sheetmetal edges, and failed wire splices. Inspect the wire plugs for corroded, bent or pushed back wire pins.


P1694

P1694 Fault In Companion Module. No CCD/J1850 bus messages received from the power train control module-Aisin transmission.

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

Possible Causes:

When the CPS short circuits the engine computer (PCM) shuts down to prevent damage to itself. As a result, there is no communication (P1694).

Disconnect your crankshaft position sensor then put the ignition key in the on position. If the instrument cluster starts to work, once the CPS is disconnected, then you know it is shorted. You can verify this by testing the CPS with an ohmmeter.

Inspect the wire harnesses for damaged wires, broken wires, or chafed/melted wire insulation. Inspect and test the CPS wire plug and wire harness for loose connection pins, corrosion, and damaged wires. Inspect, clean, and tighten firmly the two ground wires at the ignition coil. They also are ground locations for the transmission computer.


In the past there have been reports that the Transmission Control Module (TCM) failures and Remote Keyless Entry (RKE) module failures have caused similar symptoms and faults. Note that the RKE module is on the CCD Bus. Try unplugging the RKE module and try unplugging the TCM and see if the NoBus message goes away and all gauges work. If so, replace the TCM or RKE.

Engine sensor wire harness/wire plug issues, a faulty CPS, or a faulty TCM should be the first suspects for a P1694.


Additional reading >> http://www.naxja.org/forum/showthread.php?t=63167
 
Last edited:
Tim - Thank you for the guidance. Here is an update:
Replaced the TCU. Cleared all codes. Ran it for an hour, now the TPS sensor codes popped up. Replaced TPS with oem TPS. Cleared codes.

Runs good. No Codes, but the voltage on the bus is still low.

I am going to replace the PCM.

Any recommendations for a rebuilt PCM that I can order online? Most of these place have pretty bad ratings.
 
Have you done all your grounds? When I had a bus failure on my 01 it was because I forgot to put the dipstick ground back in after changing the tranny.
 
Sorry to hear that, my 01 was a never ending headache that ultimately was parted out and sent to the scrapper. My hate for the 00-01 xjs is well known here. It really just seems like the changes made in those last 2 years to appease emissions were not well thought out or tested. It really seems like those last ones seem to have the most and weirdest computer/electrical problems coupled with the crack prone head just makes them yuck.. IMHO 1996 is the best year, I love my 95 but sometimes I do wish it was obd2.

Have you reflowed the solder in the dash? I've never heard of it on an xj but neons of a similar vintage would have running issues similar to this that was caused by cracked solder in the cluster. Probably not it, but its a thought. The ecm is still in my old 01 at the local yard but I wouldn't recommend it, like I said, it was junk.
 
Still trying to figure out why the CCD BUS voltage is low. It is reading .3v on pin 3 and .09 on pin 11.

Replaced PCM, cleared codes, and runs good with no codes, but the voltage is still low on the CCD BUS. I've checked grounds.

It appears the 2.5V originates at the gauge cluster for BUS. I tested the gauge cluster and operates fine. Is it possible the cluster is bad with low voltage?

There is no SKIM, disconnected keyless entry module, disconnected and replace the TCM, none had impact on voltage.

What other modules / sensors could cause the voltage drop?

Thanks in advance.
 
Update:
I went back and tested continuity across the entire CCD Bus systems.

I got a 27 ohm reading between the PCM and TCM, on the BUS+ BK/WH wire.

Can you provide direction on how to trace this?

My initial thought is to check the C100 connector, and then looking at splice location.

Could it be a sensor/module off of the TCM causing the resistance?
 
If you did a point to point reading of the wire there shouldn't be any resistance and there should be no "components" to give you any false readings. If this is all followed correctly then you either have a bad wire or any splices/connections with corrosion. I always use No-lox on any connection I touch.
 
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