CCKen

Gauges haven't worked in three years! No wonder we haven't heard from you about low oil pressure. LOL

PUNISHER

LOL! I have manual gauges in a pillar mount. No way would I run without knowing either one. Now the gas gauge would be nice but, I have it down pretty good. Every time I stop for gas it takes 12 gallons..

PUNISHER

Ok, from C3 socket 28 to TCM socket 6 I get 2.0 Ohms and from C3 30pin socket to TCM 7pin socket I get 1.6 Ohms. Hooked C3 back up, hooked battery back and left the TCM unplugged. Still no fuel pump and no start.

So is it time to start parting it out? A lot of people keep insisting it's the CPS but, it's new and from what I have read, the fuel pump should still work.

CCKen

Those resistance values are below the 5.0 Ohm limit given in the diagnostics tests so I would think the wires are okay. The next step in the diagnostics is to replace the TCM. Still no results with the TCM disconnected just suggests that another module may be corrupting the CCD Data Bus.

The CCD Data Bus operates on the 2.5 (+) (-) circuit voltages. A module that generates 5 volts on the bus is called a Bias module. The terminating resistors in the PCM converts the Bias 5 volts to the 2.5 volts. I thibk that the Instrument Cluster is the Bias Modules in the XJ.

SOP for toubleshooting a corrupted CCD Data Bus is to start disconnecting modules on the bus until the 2.5 volts returns. The Instrument Cluster would be the last module in line, i.e., it would not be disconnected. With all modules disconnected from the bus except the PCM and Instrument Cluster, the bus voltage should read around 2.5 volts. If not, the Instrument Cluster wiring to the PCM or its connectors may be defective.

You might want to start disconnecting modules and take voltage readings at the DLC like you did before after each module is disconnected.

Do you have a Sentry Key Immobilizer system?

Does the fuel pump run for a few seconds when you initially turn the key to RUN, before cranking?

Have you tried disconnecting the crank sensor and see if the instrument cluster comes back?

Check the supply voltage to the crank sensor for 5 volts. If you disconnect the CPS connector and look at it, pin socket 3, is on your right as you look at it, this is the 5 volt supply pin (Organge wire). With the key in RUN, and using your voltmeter, measure the voltage from pin socket 3 to ground (engine structure). no voltage indicates open wiring or a dead PCM. Very high voltage indicates a short to battery voltage. Very low voltage would indicate high resistance between the PCM and the CPS. We just want to see what the PCM is doing with its 5 volt sensor supply voltage.

PUNISHER

Do you have a Sentry Key Immobilizer system? No I do not.

Does the fuel pump run for a few seconds when you initially turn the key to RUN, before cranking? Nothing at all from the fuel pump..


Have you tried disconnecting the crank sensor and see if the instrument cluster comes back? Several times and today after I unhooked the TCM and hooked it back up, my odometer started working again..

Check the supply voltage to the crank sensor for 5 volts. If you disconnect the CPS connector and look at it, pin socket 3, is on your right as you look at it, this is the 5 volt supply pin (Organge wire). With the key in RUN, and using your voltmeter, measure the voltage from pin socket 3 to ground (engine structure). no voltage indicates open wiring or a dead PCM. Very high voltage indicates a short to battery voltage. Very low voltage would indicate high resistance between the PCM and the CPS. We just want to see what the PCM is doing with its 5 volt sensor supply voltage. Will do this tomorrow and see what I get.

As always, thanks again!!

PUNISHER

Yesterday I had a friend of a friend stop by. He works on all the VDOT vehicles and is an ASE tech. He looked things over for a few minutes and also hooked up his new scan tool. Once he was done he looked at me and said that I have checked everything that he would have checked.

So after he left, I pulled the PCM ( battery negative unhooked) and looked at all the pins to make sure none were bent or possibly broken. The only thing that I could see was a melted look on pin #9 right at the base of it. Only thing is, there is nothing in the plug itself going to pin #9 so I am not sure if that is really an issue. The PCM is a remanufactured unit with a date tag on it of 01/08.

During all the testing that went on yesterday the odometer quit working again. When I unplugged the TCM and plugged it back in, the odometer started working again. So I am planning on installing the PCM back in and checking the 5V to CPS tonight and see what I get there. Then if I have the 5V needed there, it's time to unhook the gauge cluster and see what happens there!

CCKen

The PCM and TCM are prime suspects.

Remanufactured PCM's are not always up to par. You may want to consider getting another one. OEM part number 56041 277AD. '97 XJ, 4.0 engine, AW4 transmission, Federal Emissions. part number is for 1997 only, other years won't work.

TCM part number is 5602 7951. Again, for 1997 only, other years won't work. Consider replacing the TCM as well/or first.

Instrument cluster connectors are addressed by a Technical Service Bulletn that covers your year XJ. The TSB has you splicing in new copnnectors. Kits are available from the dealer. Maybe you should call them and ask about getting a kit.

If, by chance, someone packed dielectric grease in the Instrument Cluster connectors - get rid of it. Big mistake using that crap. It's actually an insulator and if the connector pins are borderline not making contact it only serves to make the contact worse.

Here's the sensor pinouts for the instrument cluster connectors. Note that C2 has the CCD Bus pins. Also, to avoid confusion, here's a pic of which connector is which.

PUNISHER

It wouldn't be the cam shaft sensor causing this would it? I was just reading about that a few minutes ago causing issues with "no start".

I have a PCM and TCM in my watch list on Ebay. $159 for the PCM with a life time warranty and $100 for the TCM with the exact part number as the one I have. Both with free shipping!

The ASE tech that stopped by yeaterday told me that $159 for the PCM was a good buy and from looking at my jeep it was worth spending the money. He said "I am sure you have spent more for less" in parts for this thing over the years". Of course he is right plus, $159 is a lot cheaper than what a shop would chage me.

CCKen

The camshaft sensor would not cause a no start problem. The cam sensor is used primarily for fuel injector synchronization.

Make sure the PCM and TCM you have lined up are the part numbers I gave you. Double check my numbers with the numbers on your installed units. My numbers came from the 97-99 parts catalog.

PUNISHER

Will do! I wrote the number down off of the TCM on Ebay and compared that number to the one I have and they matched. I will double check the numbers to make sure when I get home.

PUNISHER

Installed the PCM and checked the voltage to the CPS and I have the 5 volts needed. I pulled the dash apart and checked resistance from plug 2 C1 to C3 pin socket 28 and got 1.0 Ohms and from plug 2 C2 to C3 pin socket 30 and got 1.2 Ohms.

I ordered the PCM and TCM off Ebay, maybe I shouldn't have done it but, I feel that this has been diagnosed about as far as anyone would have taken it. So I have no regrets on ordering parts..If that makes sense!

PUNISHER

CCKen,

So far I have changed the PCM, TCM, CPS, JB and instrument panel. Cleaned all the plugs going to JB with a stiff bristle brush and contact cleaner. Also cleaned the plugs for the instrument panel/cluster. Cleaned the TCM plug and one BIG white plug just above with an M8 bolt going through it. It looked important so I cleaned it as well.

With all the above parts changed out. I am still getting 60 Ohms across Pins 3 and 11 and .2 Volts across pins 3 and 4 or 5 and 11 and 4 or 5.

CCKen

Junkyardjeep had a similar problem. Reading 60 Ohms with everyhting plugged in and 120 Ohms with the instrument cluster removed. A replacement cluster cured his problem. You might want to read through his thread and see if it will help any.

https://www.cherokeeforum.com/f2/all...orking-167111/

PUNISHER

I decided to pull the airbag control module last night and open it up being the JB and TCM were all mud soaked. Well the airbag module was really bad with packed dried up mud.

With that unhooked and the battery hooked back up, I am getting 2.48V across pin 3 and 4 and 2.48V across pin 11 and 4 but, I still have 60 Ohms with the battery unhooked across pin 3 and 11. I unhooked the TCM and checked the Ohms again and still had 60 Ohms. So making some headway but, still not there yet!

CCKen

Are you sure your instrument cluster is okay. Junkyardjeep had a similar problem where with his cluster plugged in he got 60 Ohms and with it unplugged he got 120 Ohms. He replaced his cluster and it fixed his problem.

Those voltages look okay.