TCM PCM PROBLEM ANY HELP NEEDED!!!!

error code 1698 found it out at auto zone. pulled the entire PCM out and the TCM out as well cleaned everything inside last week. 99 XJ Sport. Went to visit my girl this week in Maine and now I'm stuck here for the night (which I'm not complaining about) with my gf and my XJ is doing something stupid. After I hooked everything back up inside I checked a bunch of the connections with a multi-meter everything checked out good so far. I did the whole hold down the odometer button three turns to on and then let it do it's thing and everything was running great. Did again when I was leaving and so I drove it back, pulled the speed sensor outta the transfer case and checked to see what the little cog inside was looking like. Can't open the rest up becase the bolt in there is pretty much rusted right in there so I can't look to see if the "eye" is clean. Then went drove it around and everything was fine until I stopped at a light. Truck instruments went dead and "no bus" across the odometer. My question is what the hell is going ON!!!!! I out the truck in neutral and the RPMs go up not that the Tach is registering but you can hear the engine. Put it into drive or reverse and everything calms back down. Neutral Position switch????? JUST A BAD FRIGGIN JEEP!!!! Don't know what to do, I let off the gas and when the tach gets low towards the 600 range it seems to have the problem. but the truck could be moving or sitting still it's happen in both cases. sorry for the long post but really need some serious help, ask anyone you think might know please!!!!!

another thing where is the Neutral position switch on a 99 XJ anyone know???

VTEK1 said:

where is the Neutral position switch on a 99 XJ ?

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Neutral Safety Switch - NSS. Passenger side of the transmission.

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that is a sweet picture, it's wort more to me than words thanks a lot I owe you a beer

Crank sensor. Disconnect it and see if the "no bus" goes away.

You might appreciate this as well. http://go.jeep-xj.info/HowtoNSSrebuild.htm

how safe is it to disconnect the cranksensor will it mess anything up. Do it while it's running or not. I would assume not while it's running. the problem only happens sometimes and lately it hasn't been happening. another question how much does it cost to get a rear and/or front main seal done I think my XJ is leaking a little too much now. what about transmission lines? something I could do myself?

trucks totally dead now, the NSS looks like it could be adjusted and looked at the bellhousing to find crank sensor but I can't find it. everything I checked the TPS, speed sensor and those are all taken care of. Speed sensor kind of sticks a little in one place nothing to serious but should it stick a little??????? I think it's something to do with the PCM because these is a straight connection between the TCM and the PCM. I think the no bus is coming from the PCM and there is something wrong with that. What would the Crank shaft sensor do to mess up the TCM. I know they are on the same circuit. sry for long post. Going to have to shell out that money for the dealer to look at it and replace it.

Code P1698 - No CCD/J1850 Message From TCM. No CCD/J1850 messages received from the electronic transmission control module (EATX) or the Aisin transmission controller.

NSS problem means it won't crank at all. Wiggle the shifter lever in P and then in N while trying to make it crank. Look for the back up lights when the shifter is in R.

CPS will cause it to crank and crank and crank, but never fire up. CPS is located on the drivers side, at about 11:00 on the bellhousing.

The Jeep will run and drive if the speed sensor is goofy, but it may run oddly or light the Check Engine Lamp.

The most likely cause of it cranks and cranks but won't start up is the Crank Position Sensor (CPS). CPS failure is very common. The CPS can stop working with no warning or symptoms and the motor will not run.
Symptoms -

Fuel gauge and voltage gauges may not work or display properly.

You sometime will have No Bus on the odometer after 30-60 seconds.

NO spark.

Fuel pressure is OK

If the CPS is failed sometimes the OBDII code reader cannot make a connection to the computer or cannot read Check Engine Light/MIL codes because the CPS has failed.

Diagnostic steps to confirm the CPS is the cause of your no-start

You might be able to verify a bad cps, by unplugging it, and turning the ignition key to on. If the voltage gauge and/or the fuel gauge now displays correctly, replace the CPS.

Exchange the fuel pump relay and the ASD relay with one of the other similar ones in the PDC to eliminate the relays as the cause of the no-start.

Eliminate the NSS as a cause of no start. Wiggle the shift lever at the same time you try to start. Put the transmission in Neutral and do the same. Do the reverse lights come on when the shifter is in Reverse?

Begin with basic trouble shooting 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 and replace as needed. Do the same for the grounding wires from the battery and engine to the Cherokee's frame/body.

CPS Testing


Crankshaft Position Sensor Connector





TESTING PROCEDURE 1991 – 2001 4.0L H.O. engines
1. Near the rear of intake manifold, disconnect sensor pigtail harness connector from main wiring harness.
2. Place an ohmmeter across terminals B and C (SEE Image). Ohmmeter should be set to 1K-to-1OK scale for this test.
3. The meter reading should be open (infinite resistance). Replace sensor if a low resistance is indicated.

TESTING PROCECURE for 1987 – 1990 4.0 L engines

Test # 1

· Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the CPS and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 - 275 ohms. If the CPS is out of that range by much, replace it.


Test # 2

· You'll need a helper for this one. Set the volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your helper cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.

The NSS isn't the problem because the reverse lights come on, the Crank shaft sensor I haven't tested. I checked the TPS that checked out with gradual increase in resistance. Now the Jeep is at my house in MA (i'm in Maine for school) it starts but then the NO BUS comes up and the speedometer and the tach don't work but the other gauges read. Then when I put it into Neutral or Park it idles pretty high. Anymore ideas thanks a lot for your help.

Some of the newer cherokees have two connectors on the panel that go into another pair of connectors that are part of the dash assembly. Meaning they are not plugs on the end of wires like the old style...

Think of them as in outlet in your house. The Instrument cluster being a cord and the dashboard being the outlet. Pull the IC out and clean the plugs on both, then re-install the IC and see it that helps.

I'm glad all my jeeps are Renix. No bus message just sucks trying to diagnose.

Kinda sounds like a CPS problem, at least part of the problem.

I replaced the alternator and the problem went away. But today driving I had a problem. I put the truck in park and then back in drive no problems. Had my buddy drive it and it did it to him he did the same thing and everything began working fine. Please help from anyone.

I've cleaned the Instrument cluster twice now and it doesn't really seem to help. like i said the alternator seemed to fix the problem but now it's showing up again. how could I test each connection in the dash to see if there is a short or open in one of the wires? This truck also had a alarm system that was pretty much just torn out but the truck has been running fine for over a year so I don't think that would be anything.

VTEK1 said:

I've cleaned the Instrument cluster twice now and it doesn't really seem to help. like i said the alternator seemed to fix the problem but now it's showing up again. how could I test each connection in the dash to see if there is a short or open in one of the wires? This truck also had a alarm system that was pretty much just torn out but the truck has been running fine for over a year so I don't think that would be anything.

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Have you checked the Battery and cables? A problem connection between the alternator and battery can cause problems. I think the voltage regulator is in the PCM in 99s! Have you checked the running voltages?
I am still trying to figure out what you are saying is happening, or going wrong. Can you be more precise?

I drove his XJ yest.

Pulled out of a parking lot and everything was fine. Slowed to make a right turn and the air bag light came on. About 5 seconds later the NO BUS code popped up on the IC. While the code was up, the truck refused to down shift into first even after a complete stop. I physically had to put the truck into first gear with the shifter.

After pulling out in first gear I took a left turn into a parking lot. As I approached the entrance I hit a small bump and the NO BUS error vanished and the truck shifted fine with no further input from me.

My money is still on a connection issue.

I was sitting there pondering on how the air bag and tranny are related. IIRC the airbag deployment is only allowed after a certain speed is reached along with input from the impact sensors. This is done to keep the airbag from blowing in your face on a minor fender bender.

The Speed sensor or associated wiring would be my best guess.

I would look for critical hot wire partially grounding out through worn insulation, or a bad connector at the battery or main computer. There may be TSB out on that problem for that year!

I checked the battery and it's running at 13 volts, just like it should. I replaced the negative cable a couple of months ago because I was getting this distributor "whine" in my radio thought it might be a bad ground. Turned out it was the wire from the coil to the distributor was a little loose. Anyways, if I'm driving the Jeep loses it's speedometer and tach but all the other gauges work and it won't shift. Then "no bus" appears on the odometer and the truck I think stays in like 3rd gear and kind of goes into like this "safe mode". Not sure whats going on and I'm without a vehicle right now. I hope this helps.

VTEK1 said:

I checked the battery and it's running at 13 volts, just like it should. I replaced the negative cable a couple of months ago because I was getting this distributor "whine" in my radio thought it might be a bad ground. Turned out it was the wire from the coil to the distributor was a little loose. Anyways, if I'm driving the Jeep loses it's speedometer and tach but all the other gauges work and it won't shift. Then "no bus" appears on the odometer and the truck I think stays in like 3rd gear and kind of goes into like this "safe mode". Not sure whats going on and I'm without a vehicle right now. I hope this helps.

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If the engine was running when you tested it (which is what I was suggesting that you do) 13 volts is too low. Unless you have AC running, Blower on High speed, electric coolant fan runing and headlights on, and even then it should still be at least about 13.6 volts or a little higher. With all that stuff off, engine running, it should between about 14 to 14.6 volts right after starting the engine.

When he checked I was on the phone with him, IIRC it was 13.9