[Jeeperez]

Hello everyone

Recently bought a 1998 Cherokee with 4.0/Auto
around 178K



Picked her up for 1100 on the account it wasn't running. Did some research and replaced the CPS (Crankshaft Positioning Sensor) and she fired right up no problem.

About a month later she started having charging issues. It wasn't charging the battery. First changed the alternator, no luck.
Then I changed all plugs, wires, cap and rotor, terminals..all brand new. Still no luck.

At this point, all of my gauges decided to stop working as well. All my indicators work, highbeams directionals..they all display but i'm not getting a readout on the gauges.

I decided to have the PCM (Powertrain Control Module) rebuilt seeing how the Cherokee has an internal voltage regulator. It fixed my charging issue but i'm still left with no guages.

What does happen is when I fiddle with the C3 Connector on the PCM, the gauges with temporarily work.



I went through the engine compartment yesterday and redid all the grounds, and currently have the dash completely apart. I'm figuring its a ground because my Radio also has engine noise but is fine when the engine is off.

Also...sometimes when I go to start it doesn't fire on the first try. Either have to continue cranking or try again before the engine fires up. Only sometimes though.




So if anyone can help please do I cant figure this out!!

[CJ7-Tim]

PCM failure is very highly unlikely. Charging issues are usually the battery, the alternator, or the wires. Repair or replace as needed. Dead gauges are also common, the connector on the back of the gauge cluster may need cleaning or tweaking. Slow starts are most often a failed Check Valve on the fuel pump.


Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds.

Have the battery, starter, and the alternator Load Tested for proper function in a test machine that applies a simulated work load. Handheld testers are inaccurate and will often pass faulty parts.



Check Valve

When your 1997 to 2001 Cherokee won’t start on the first try day after day, the first thing to suspect is a failed check valve on the fuel pump. The fuel pump check valve is supposed to hold pressure in the fuel line while the engine is off. The check valve is located on the fuel pump and located in the gas tank. A failed check valve allows the fuel to drain back to the tank. This results in the following symptoms:

SYMPTOMS

• Longer than normal cranking times
• Never starts on first try, almost always starts on the second try
• Rough idle for a few moments of idling
• Rough running for first ½ block of driving
• Little or no fuel pressure at the fuel rail test valve similar to this -

1- Key in on position; fuel pump primes for 2 seconds then stops. 0 PSI
2- Cranking over the engine. 2-3 PSI
3- Engine starts and idles for 20 seconds. < 5 PSI
4- Engine idles and fuel pressure creeps up to 45-50 PSI.


POSSIBLE CAUSES

• Failed check valve on the fuel pump in the gas tank.
• Leaky fuel injector(s) may be the true cause of your problem, but more likely they are simply contributing to the check valve issue.

Testing of the fuel injectors should show if any are faulty and are allowing fuel to drain into the cylinder. Either problem can allow heat soak to vaporize the remaining fuel in the fuel rail and you may be dealing with a bit of vapor lock as well, especially in warmer weather.

1. Connect the gauge at the fuel rail and start the engine. The gage should read 49 psi plus or minus 5 psi.

2. Turn the engine off and immediately clamp the fuel line just ahead of the fuel tank. Watch the pressure gage and see how long it takes to loose pressure.

If the pressure remains at 49 psi for an extended period of time then the problem is in the tank - probably the check valve. If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky injector.

There are a few solutions to the problem –

1. Turn the key to ON for 5 seconds and let the fuel pump prime. Turn the key to OFF, turn the key back to ON for 5 seconds, start the engine.

2. Crank the engine for 3-5 seconds, pause, and crank the engine again. It will almost always start on the second try.

3. Replace the fuel pump assembly in the gas tank. The check valve is not a separate part and cannot be serviced. This is both expensive and time consuming because you have to remove any hitches and skid plates and then remove the gas tank from the vehicle.

You can use solutions 1 or 2 for as long as you want to, they do not harm anything and the fuel pump will continue to function for many more years.


If you do replace the fuel pump assembly, purchase a high quality OEM style unit. Some cheap aftermarket fuel pump assemblies, like Airtex, don’t hold up and fail completely within 12-18 months.

[Jeeperez]

Forgot to add..

The codes that im getting are

P1682
P1698..No trans bus message
P1694..No CCD Bus -/+

[Jeeperez]

Originally Posted by CJ7-Tim

PCM failure is very highly unlikely. Charging issues are usually the battery, the alternator, or the wires. Repair or replace as needed. Dead gauges are also common, the connector on the back of the gauge cluster may need cleaning or tweaking.


Perform routine maintenance of the start and charge systems. Remove, clean, and firmly reconnect all the wires and cables to the battery, starter, and alternator. Look for corroded or damaged cables or connectors and replace as needed. Do the same for the grounding wires from the starter to engine block, and from the battery and engine to the Jeep's frame/body. You must remove, scrape, and clean until shiny, the cable/wire ends, and whatever they bolt to. Jeeps do not tolerate low voltage, bad connections, or poor grounds.

Have the battery, starter, and the alternator Load Tested for proper function in a test machine that applies a simulated work load. Handheld testers are inaccurate and will often pass faulty parts.

Thanks for the reply. All of this was done, my father owned a mechanic shop so we have all proper equipment.
The charging issue was addressed and fixed. Just inoperable gauges at the moment.

Would a bad CPS do all of this? I bought the replacement at Autozone.

[CCKen]

Originally Posted by Jeeperez

Hello everyone

Recently bought a 1998 Cherokee with 4.0/Auto
around 178K



Picked her up for 1100 on the account it wasn't running. Did some research and replaced the CPS (Crankshaft Positioning Sensor) and she fired right up no problem.

About a month later she started having charging issues. It wasn't charging the battery. First changed the alternator, no luck.
Then I changed all plugs, wires, cap and rotor, terminals..all brand new. Still no luck.

At this point, all of my gauges decided to stop working as well. All my indicators work, highbeams directionals..they all display but i'm not getting a readout on the gauges.

I decided to have the PCM (Powertrain Control Module) rebuilt seeing how the Cherokee has an internal voltage regulator. It fixed my charging issue but i'm still left with no guages.

What does happen is when I fiddle with the C3 Connector on the PCM, the gauges with temporarily work.



I went through the engine compartment yesterday and redid all the grounds, and currently have the dash completely apart. I'm figuring its a ground because my Radio also has engine noise but is fine when the engine is off.

Also...sometimes when I go to start it doesn't fire on the first try. Either have to continue cranking or try again before the engine fires up. Only sometimes though.




So if anyone can help please do I cant figure this out!!

This ground (pic) is supposed to suppress radio interference. My bolt at the firewall was very rusty and the strap terminal end was corroded. The terminal end at the rear head bolt/stud was clean. You may want to check this. You don't need to replace this braided strap with a giant battery cable (like some suggest), just verify that the strap is serviceable.



Verify that the alternator and battery connection at the end of the PDC are free from corrosion and are secure. Remove the small cover at the end of the PDC to access the connections. See pic below. The cable on your left with the green insulation is the B+ cable from the alternator.

[Jeeperez]

CCKen,

Thanks for the reply. The braided wire on the firewall was removed, cleaned, firewall sanded to bare metal and reinstalled but still having engine noise in the radio. But I didn't redo the same connection on the engine side

And i'll redo the connections at the PDC like you suggested and see what happens

[CCKen]

Forgot to mention that there is a Technical Service Bulletin (TSB) addressing 98 instrument cluster connector replacement. Check the connector harness wiring near the instrument cluster and see if there are butt splices in the wiring. If so the TSB was C/W, if not it may need the new connector (per the TSB).

INFO: PCM connector C3 does have the CCD Data Bus (+) and (-) connectors.

[CCKen]

Originally Posted by Jeeperez

Thanks for the reply. All of this was done, my father owned a mechanic shop so we have all proper equipment.
The charging issue was addressed and fixed. Just inoperable gauges at the moment.

Would a bad CPS do all of this? I bought the replacement at Autozone.

A quick check would be to disconnect the CPS and see if the gauges return. A bad CPS will corrupt the CCD Bus.

[CCKen]

Originally Posted by Jeeperez

Forgot to add..

The codes that im getting are

P1682
P1698..No trans bus message
P1694..No CCD Bus -/+

Did these codes show up after you fiddled with the PCM C3 connector? Did you disconnect C3?

Any bad module on the CCD Data Bus will set these codes (more often the TCM). The instrument cluster is a module on the Bus.

[Jeeperez]

Originally Posted by CCKen

Did these codes show up after you fiddled with the PCM C3 connector? Did you disconnect C3?

Any bad module on the CCD Data Bus will set these codes (more often the TCM). The instrument cluster is a module on the Bus.

Yes these codes as well as the check engine light appear after fiddling with the C3 connector. I already checked for loose connections on the connector itself.

I'll try disconnecting the CPS as well.

[CJ7-Tim]

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:
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 the CPS or CPs wires are shorted. You can verify this by testing the CPS and checking continuity on the CPS wires.

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

P1694 Diagnostic Procedure
1. Using scan tool, clear TCM DTCs. Start engine and let idle for at least 2 minutes. Using scan tool, retrieve TCM DTCs. If DTC P1694 returns, go to next step. If DTC P1694 does not return, go to step 5.

2. Check instrument cluster gauges for proper operation. If fuel gauge and speedometer operate properly, go to next step. If fuel gauge and speedometer do not operate properly, see appropriate INSTRUMENT PANELS article.

3. 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 as necessary. If no problem is found, check for broken, bent, backed-out or corroded terminal pins. Check for chafed, pierced or partially broken wires inside insulation. Repair as necessary.

[Jeeperez]

I disconnected the CPS to see if it was faulty and the guages did NOT return. So its not that.

I cleaned, bent and applied dielectric grease to the pins on the back of the cluster. Gauges did return, 6 times turning the key on and off. As soon as I turned the engine on, they froze and shortly shut off. Playing with any of the connections did not fix the issue afterwards.

[Jeeperez]

Originally Posted by CCKen

Forgot to mention that there is a Technical Service Bulletin (TSB) addressing 98 instrument cluster connector replacement. Check the connector harness wiring near the instrument cluster and see if there are butt splices in the wiring. If so the TSB was C/W, if not it may need the new connector (per the TSB).

INFO: PCM connector C3 does have the CCD Data Bus (+) and (-) connectors.

Can you tell me where this Service Bulletin is posted?
I'd like to get a copy for records

I checked the wiring at said connector and it appears to be stock and untouched.

[CCKen]

Originally Posted by Jeeperez

Can you tell me where this Service Bulletin is posted?
I'd like to get a copy for records

I checked the wiring at said connector and it appears to be stock and untouched.

Refer to this link:

http://www.jeepforum.com/forum/f12/n...ctures-160897/

By any chance did you try hitting the top of the instrument panel to see if the gauges come to life? If they do, it usually indicates a bad cluster or the connector.

[Jeeperez]

Originally Posted by CCKen

Refer to this link:

http://www.jeepforum.com/forum/f12/n...ctures-160897/

By any chance did you try hitting the top of the instrument panel to see if the gauges come to life? If they do, it usually indicates a bad cluster or the connector.

Thanks for the link

I did try that, quite a few times
I even went as far as bending the prongs on the back of the cluster and putting dielectric grease on them to better the connection to no avail.

If this issue isn't solved by the 13th i'm bringing it to the Jeep dealer to be diagnosed.