P1694 P1698 P700 codes - did all the tests?

[97-98-99]

97 XJ 4.0 Auto 204k miles

Car starts, runs, shifts without any issues. Went to get it inspected and P1694 P1698 OBD codes popped up (I also get the P700 code now when I put the reader on).
I did a search and found some old posts with a lot of great diagnostic info. From what I can see, all the tests checked out good:
At the DLC, CCD(+) and CCD(-) voltages were ~ 2.4 volts
DLC pins 3 to 11 read 60 ohms
PCM plug C3 pins 28-30 read 119 ohms
Continuity between PSM C3 harness pins 28 and 30 to their corresponding DTC pins is good.
Continuity between PCM C3 harness pins 28 and 30 to the corresponding pins on the TCM harness is good.
I also cleaned the grounds at the coil mount and re-seated the instrument cluster.
Also got another TCM , no change.
Can it be the PCM? Is there any other test I can do?
One thing that I didn't see in any of my searches - when I clear the codes, the CEL never comes on by itself in normal driving. It only turns on when I put the scanner on and pull the codes.
Thanks in advance for the help. I can't pass inspection without getting this figured out.

[RCP Phx]

The one thing you didn't check for is insulation resistance between the wires.

[Tim_MN]

If you have both a P1694 and P1698 suspect a faulty Crankshaft Position Sensor (CPS). The CPS must be tested before you proceed. In the past there have been reports that the TCM has caused similar fault(s). Try unplugging the TCM and see if the NoBus message ( if present ) goes away and all gauges work. If so, replace the TCM.

Inspect and test the CPS wire plug and wire harness for loose/bent/damaged 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.

P1694 Fault In Companion Module.
No CCD/J1850 bus messages received at the power train control module (PCM) from the AisinWarner Transmission Control Module (TCM). P1694 will set if no CCd bus messages are received from PCM for 20 seconds or invalid messages are received for 20 seconds.

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.

In the past there have been reports that the Transmission Control Module (TCM) failures and 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.

Read this >> http://www.naxja.org/forum/showthread.php?t=63167

P1698 No CCD Messages Received From PCM.
Bus communication failure to PCM. A "Companion DTC" was set in both the ECM and PCM.
Possible Causes:
- CCD Bus (-) circuit open between PCM and TCM.
- CCD Bus (+) circuit open between PCM and TCM.
- Engine control module (ECM) harness is open or shorted.
- Engine control module (ECM) circuit poor electrical connection.
- Failed engine control module (ECM).

Read this >> https://www.jeepforum.com/forum/f11/...odule-1359085/

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 voltage and fuel gauges start to work once the CPS is disconnected, then you know the CPS or CPS wires are shorted and is the root cause of the codes. You can verify this by testing the CPS and checking continuity and voltage on the CPS wires.

P1694 Diagnostic Procedure

1. Check instrument cluster gauges for proper operation. If fuel gauge and speedometer operate properly, go to next step. If fuel gauge and voltage meter do not operate properly, test the CPS.
2. 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 wiring as necessary. If no problem is found, check for broken, bent, backed-out or corroded wire terminal pins. Check for chafed, pierced or partially broken wires inside insulation. Repair as necessary.

[97-98-99]

Thanks for the reply! I checked the resistance of the two wires between the PCM and TCM. 1.2 and 1.4 ohms. Also checked the CCD+ and - bus voltage at the DTS - both were 2.4 volts. Cleaned the grounds at the coil mount, too. Got a used TCM, still the same.


I'll try unplugging the RKE, that's in the headliner by the rearview mirror, right?



If the CPS is bad, would it still start/run? I though a bad CPS would prevent it from starting. Car starts and runs fine.
One other thing, don't know if it means anything - if I clear the codes, the CEL light never comes on no matter how much I drive. And when I first put the reader back on, it also says no codes present. It's only when i re-scan do the codes pop up. The only way I found out I had the problem was when they scanned it at the inspection.

[Tim_MN]

1997-2001 RKE module is the green circuit board in the dome lamp or the optional overhead console.

Typical CPS Symptoms, (not all symptoms may be present, or occur at the same time) -
- Random stalling
- Starter cranks and cranks but engine won't start up
- Fuel gauge and voltage gauges may not work or display properly.
- You sometimes will have NoBus displayed on the odometer after 30-60 seconds.
- A failed CPS/CKP may or may not throw a CEL trouble code.
- Fuel pump should run and prime for 3-5 seconds.
- No spark at the spark plugs.




.

[97-98-99]

Don't think it the CPS then, although the fuel gauge intermittently goes to zero then back to normal (no issue with the volt meter and I don't have any of the other of those symptoms).
I disconnected the RKE module and thought that did it but turns out not to.
The scanner I have scans Global and Jeep specific codes separately. Initially when I scan the global codes, it's clear, then when I do the Jeep codes, the airbag light turns on. If I re-scan global, the airbag light goes out, the CEL light goes on and I have P1694 p1698 and P700 in different combinations between global and Jeep functions (I get a comm error when I try to scan the airbag codes, but that happens on my other jeeps too) . Eventually, I can clear them all and they stay clear until I disconnect the reader and start again - the cycle repeats when I start again.
On the fuel gauge, when it drops out, I get a P0463 Fuel level sender high code, but that seems to be independent of my main problem, but I don't know.

Can the airbag light coming on be related to the cause or just another symptom? I'm a little paranoid about the airbags going off - can the module be safely unplugged after I disconnect the battery for 10 minutes? Is that a valid test?

Any other suggestions? Sorry for the long post, but I'm about ready to give up.

[Unclewolverine]

Air bag light points to the clock spring being worn out, which can cause a host of other issues. I would start there.