PUNISHER

Year:1997 Cherokee
Trans:AW4

Okay, bare with me as I explain this..

Two weeks ago I drove the XJ to work on a Monday, no issues, ran like a champ. Came out from work, fired it up and it was sitting there sputtering like it was starving for fuel. I then shut it down, waited a few seconds and turned the key, heard the fuel pump run, waited 5 seconds and started it up. It idled fine, drove it the 22 miles back home, drove it in the garage and shut it down.
Went out last Saturday to fire it up and as soon as I turned the switch on, the radiator fan came on. I said to myself this isn't right, hit the switch and the engine turned over fine but, no start. I posted the issue on here and got check spark and check fuel. Did all that, no spark, even held the screwdriver inserted into the plug wire in my hand because I was so darn irritated at the time. I do not hear the fuel pump engaging at all. So I bought a new CPS, which is a MOPAR part and installed that but, still no spark and no fuel pump.

Friend stopped by last night with his scan tool and pulled the P1694 code. I have been reading up on this for a couple hours now and tried the unplugging of the CPS, turning switch on, looking at gauges and such. But, after 30 seconds, I get the ol' "no bus" showing up again. So with a new CPS (yes, I know "new" means squat") and all the relays and fuses under the hood check out fine, I have rolled around the jeep on my creeper looking for any signs of a broken, burnt, chaffed wires. Nothing found there! Been all over the top of the engine looking for the same things..Nothing found!

Could it be the ECM/PCM? Or is there something else that I may have missed? I did use my test light to check for voltage at the pump. There is voltage but, my test light is very dim when checking it. Like there isn't 12 volts going to the pump, or enough to turn the pump over so to speak.

Any help is greatly appreciated..

CCKen

P1694-CCD MESSAGE FROM JTEC FAILURE

Possible Causes:

The PCM may be at fault or the TCM may be causing problems on the CCD Data Bus.

Start by wiggling wire bundles. Start at the TCM connector. See if it makes a difference. Wiggle the wire harnesses at the PCM and see that makes a difference.

Here's a schematic of the CCD Data Bus and the modules connected to it.

Test the CCD Data Bus using a digital voltmeter set at 20 VDC.

Turn the ignition key to RUN (without cranking engine).

At the DLC,

Probe (+) pin socket 3 and probe (-) pin socket 5 (and/or 4). You should see around 2.49 volts.

Probe (+) pin socket 11 and probe (-) pin socket 5 (and/or 4). You should see around 2.51 volts.

Voltages can be higher or lower a few tenths of a volt. THe 2.49 and 2.51 are perfect readings.

If any one voltage is zero or 5 volts, the PCM may be bad.

Turn ignition key to LOCK. Disconnect battery negative cable.

Using a digital ohmmeter,

Probe pin sockets 3 to 11. You should see 60 Ohms. If not, the wiring to the PCM may be bad or the terminating resistors in the PCM are bad. If you read 120 ohms, one of the terminating resistors are bad.

If the voltage readings (above) are bad try disconnecting the TCM and see if the voltages recover.

Do these tests and get back with your results.

TEST ACTION

PUNISHER

Thanks a lot CC! That is some very helpful information and a lot easier for me to understand compared to what I have read. I will bring my meter home from work tomorrow and check it out. Thanks again..

PUNISHER

Checked the DC voltage across pin 3 and pin 5 and got .2 volts. Across pin 11 and pin 5 is also .2 volts. Now I used two different meters and both showed the same results across the above pins. I double checked each one with the battery and got and they checked out fine there. Did that for my own comfort..

I disconnnected the negative battery cable and checked pins 3 to 11 and got 60 Ohms..

Disconnected the TCM and checked the voltage again across pins 3 to 5 and 11 to 5 (with battery hooked back up) and got the same .2V reading. So everythng is pointing to the PCM.

CCKen

60 Ohms is good sign. This means both termination resistors are working together.

I don't understand your statement: "I double checked each one with the battery and got and they checked out fine there."

The voltage readings are to be made with the ignition switch in the RUN position (engine not running), and the voltmeter set to the 20 VDC range. .2 volts looks like the PCM idle voltage (key OFF).

Try taking the readings again but use pin socket 4 as the ground (key to RUN). If you still see .2 volts double check the DLC pin sockets to make sure they are corrosion free and check the DLC grounds at the oil dipstick tube attach stud to make sure thay are corrosion free.

Concerning the 60 Ohms:

Check the termination resistor pack in the PCM for 120 Ohms.

Refer to the PCM C3 pinout below.

Detach the battery negative cable.

Detach PCM connector C3 (the Gray connector).

Using your Ohmmeter, read betaween pins C28 and C30 in the PCM connector socket, not the connector. You should read 120 Ohms. If you read 60 Ohms the PCM termination resistor(s) are defective. If you read 120 Ohms the termination resistor in the PCM is good..

Do these tests and get back.

Good luck.

C3 pinout:

PUNISHER

Sorry, I was talking about checking my meters to the battery to make sure that they were working properly. All the checks that I done were to the 'T' as described in the drawing.

PUNISHER

Is there a time once the neg. cable is removed from the battery before I remove the gray PCM plug? I read somewhere to wait 10 minutes before unplugging the PCM once the battery was unhooked..

CCKen

I haven't seen any precautions like that, just that the ignition switch must be OFF before disconnecting any sensor, and that the battery negative cable is to be removed before disconnecting any sensor. That being said, it's always wise to cautious and wait the 10 minutes.

PUNISHER

OK, got home and went to work. I first pulled the ground off the battery and while I was waiting I pulled the ground wires off the dip stick stud mount. Cleaned the ground with some emery cloth and a little brake cleaner. Wiped the stud off and sprayed it also.

I then pulled the C3 plug from the PCM and checked Ohms across pins 28 and 30. I got 120 Ohms so I plugged it back in and hooked the battery back up. Went back and checked voltage across pin 3 and pin 4 with the switch on and still have .2 volts. I also have .2 volts across pins 11 and 4 and 60 Ohms across pins and 11 with the switch off.

So do I have bad wiring or something else major going on? I told the wife that I will roll the jeep out the garage and part it out and get out of the jeep headache all together. Pretty upsetting when I just got my disc brake and locker done on the 8.25 sitting on my sawhorse's in the garage...

PUNISHER

Sorry again..that's 60 Ohms across pins 3 and 11 with the switch off and the battery still unhooked. I did this before hooking the battery back up. Got a little ahead of myself..

CCKen

Chill out, don't part it out.

Looks like PCM is okay but one of the CCD Bus wires is open.

You'll need to measure the resistance of the CCD Bus (+) and (-) wires between PCM C3 and the DLC.

You'll need a helper and a continuous length of wire (18 gauge will do) and your Ohmmeer. Strip back about 1/4" of insulation from both ends of the wire.

Touch pin socket C28 of C3 with one end of the wire and the other end of this wire with one probe of the Ohmmeter and the other probe of the meter to pin socket 11 of the DLC. You should read near full continuity. Repeat the process going from C30 of C3 to 3 of the DLC. Again, near full continuity.

Here's what the CCD Data Bus looks like:

Note that the Module (-) and (+) wires are gathered in two splices on the way to the PCM.

PUNISHER

Thanks a lot CCKen for all your help with this. I greatly appreciate it. I will check this out tomorrow when I get my wife involved with helping me out.. Lord help me!!

PUNISHER

Okay, pulled gray plug, negative on battery unhooked. Checked plug socket 28 to 11the and got .4 ohms. Went to socket 30 to 3 and got .4 ohms. Now, with the plug still out I checked across 3 and 11 and got 116 ohms. Plugged C3 back in and got 60 ohms again.

CCKen

Okay, lets try what the 2001 diagnostics book says about P1694.

You'll need to refer to the C3 pinout and the TCM pinout (below).

But first, reconnect C3 and disconnect the TCM and see what happens. See if it starts and runs okay and your instrument cluster is working. If not, proceed with the P1694 diagnostics. If it does work okay, consider the TCM is corrupting the CCD Bus (but do the diagnostics pin-to-pin redings frst before comdemning the TCM). TCM's have caused CCD Bus problems over the years.

Here's the two pages for the diagnostics. Disregard any reference to DRB III. Again, you'll need to refer to the PCM C3 connector pinout as well as the TCM connector pinout. You'll be going from CCD (+) to CCD (+), and the (-) pins of both. It's about the same as you did with the PCM to DLC readings, which sort of proves there's something outside of the PCM/CCD Data Bus wiring at fault.





Here's the 97 TCM pinout.



Here's the location of the TCM.

PUNISHER

Just a FYI, my gauges haven't worked since the day I bought this thing 3 years ago. I did however during all this, get the odometer back but, now it's back out again. I will try unhooking the TCM and see if it will start along with the info below.