98, cranks but doesn't start, replaced CPS, code 1694

[beakman]

hi everyone,

Well, somehow I put over 300k miles on my last XJ, and about 200k on this one, and I've never had any real problems with either, other than one starter and alternator on the first, and an alternator on the second.

I went out a couple of weeks ago, and my 98 XJ 4.0/automatic simply wouldn't start. Checked the forums, checked the codes, and figured the CPS was worth a shot. But that didn't do it.

Symptoms:
* cranks like a champ, but doesn't fire
* no spark at the plugs
* fuel pump doesn't prime when key is put in the "on" position
* code 1694 on the OBD
* only the oil pressure gauge moves a little in the "on" position, but they all operate fine if you trigger the gauge test

What I've looked at:
* fuel pump relay checked, all fuses checked
* CPS replaced (as mentioned above)
* wiggled/checked PCM and TCM plugs
* unplugged battery overnight to reset computer

So I'm still seeing 1694. I'll be checking continuity and voltage later. If I rule out wiring problems, what's more likely to need replacing? The TCM or the PCM? I don't want to throw parts at it (especially since I've already thrown a CPS at it), so I'm trying to narrow it down as best I can. Luckily there's a pullapart not too far away, and several XJs being parted out on craigslist, so I can at least try a computer on the cheap if need be.

Thanks in advance to everyone!

[Digger87xj]

Most likely the PCM is history.

[Tim_MN]

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 TCM
-CCD Bus (-) circuit open between PCM and TCM.
-CCD Bus (+) circuit open between PCM and TCM.
-Transmission CCD bus wiring damaged.

Wiring issues, PCM wire plug corrosion, one of the CCD Bus 5 volt sensors has failed, or a faulty TCM should be the first suspects.

PCM failure is very highly unlikely.

[Digger87xj]

I guess the best question to ask is whether the code is being pulled from the pcm or TCM?

[Weldingwizard11193]

I have the same issue with my 97, exactly the same. Sat in my shop all winter (it's a toy) went to fire it up and am having all the same issues you listed exactly. Hope someone can give more insight to the problem.

[go1lum]

I had a similar problem from the fuel pump wire grounding on the axle. Would blow one of the little fuses in the PDC. I think it was a 15A. It would kill my fuel pump and spark.

[Weldingwizard11193]

I've been pulling my hair out over it, I can bypass relay and the pump works great

[Tim_MN]

Originally Posted by Tim_MN

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

Wiring issues, PCM wire plug corrosion, one of the CCD Bus 5 volt sensors has failed, or a faulty TCM should be the first suspects. PCM failure is rather unlikely.

1. Unplug the TCM, and see of the CEL clears
2. Inspect and clean wire harness plugs
3. Test the TCM wire harness continuity
4. Test Transmission wire harness continuity.
5. Unplug each 5 volt sensor on the CCD Bus one at a time, and see of the CEL clears

[W2_ORZEL]

Originally Posted by beakman

hi everyone,

Hello, I know it's old thread, but how this history ended? Does your XJ fired up, and what was the issue?

[RCP Phx]

Originally Posted by W2_ORZEL

Hello, I know it's old thread, but how this history ended? Does your XJ fired up, and what was the issue?

He hasn't been on here for 8yrs!

[Tim_MN]

Originally Posted by W2_ORZEL

Hello, I know it's old thread, but how this history ended? Does your XJ fired up, and what was the issue?

Some Do It Yourself is required. Everything I posted in 2015 is still recommended as your first steps in troubleshooting.