NCDON

Tried leaving for work this morning and found my 1999 XJ cranks but will not start. I started out by removing a spark plug to see if I was getting a spark but these was none, then I connected the spark plug wire and plug directly to the coil and also no spark.

Looking for a quick fix I ran to NAPA and bought a coil but you guessed it, performed same two test and no spark. Checked for voltage at the coil plug, looks like white and green wires and no voltage, I think should have been 12v at the white wire with key on.

Borrowed a OBDII scan tool and after scanning VPW, PWM, CAN, KWP2000, ISO9141, I get message LINK ERROR!. I am wondering if LINK ERROR is telling me that my PCM is causing the problem?

I did not check to see if I am getting fuel and am not sure how to do that on a fuel injected vehicle, any advise how to check this?

Any advise on what to start checking next?

Jimbo Slice

Best practice is to get a fuel pressure gauge and hook it to the valve on your fuel rail. Quick test is to sit in the Jeep, turn key forward and listen for the pump to prime... You should be able to here it.

However, you should focus on the no spark condition for the time being. Check your crankshaft position sensor first... should be a test procedure around here somewhere.

Jimbo Slice

Here's your test procedure.

https://www.cherokeeforum.com/f51/testing-cps-5563/

fb97xj1

Clean the engine grounds. The DLC ground is the one at the transmission dipstick. If that ground is dirty, that may explain the link error. Or it could be the DLC port itself. The crank no start could be part of it, or something else entirely. Does it start in neutral?

Jimbo Slice

Right on. Here's a good link where CCKen gives some excellent info on the subject.

https://www.cherokeeforum.com/f2/obd...eading-161637/

BlueRidgeMark

Checking the presence of fuel is easy - there is a Schrader valve on the fuel rail. (same looks and functionally as a tire's air valve). Just remove the cap, push in the center pin, and see if it squirts gas at you. Make sure you are smoking when you do this, of course.

There are a number of reasons why you might not have spark. One of your relays (tucked away in the PDC, near the battery) is the Automatic Shut Down (ASD) relay. This controls power to your fuel pump, your injectors, and your coil. The ASD provides 12v to each of these. The PCM provides ground to the injectors and the coil. So, with the key on, you should see a constant 12v to the coil and to each injector. When the coil needs to fire, or an injector needs to squirt fuel, the PCM provides ground, and good things happen.

So, do a quick check for fuel (the squirt test), then swap your ASD with one of the other relays. There are a few in there that are identical - they can be swapped around. The chances of two of them being bad is pretty small, so this is a good test. Quick, easy, and free.

Another problem could be your CPS (Crank Position Sensor) or your CPS (Cam Position Sensor). Yeah, I know. Some people abbreviate the crank sensor as CkPS to avoid confusion. Either one will kill your spark, but they usually signal their impending demise by giving you some rough running engine time before they die.

Check on the relay and the fuel, and let us know, and we'll go from there.

Oh, it wouldn't hurt to check the fuses in the PDC while you're at it. Fuses can occasionally fail for no real reason. Just tired. If the fuse that feeds your ASD is gone, ain't nuthin' gonna happen!

And don't go throwing more parts at it!

NCDON

These are the results of todays tests, I think I did everything suggested.

Crankshaft Position Sensor
0.02 ohms across pins B-C. Reading from auto ranging digital meter, when touching the meter leads together it also reads 0.02 so can I assume the CPS is good? Would it be acceptable to use a jumper wire between B-C connectors at the harness side of plug to confirm CPS?

Data Link Connector.
Bottom row pin #8 from left has 12.34v when connected to top row from left, pins 3-4.
Ground wires next to trans dipstick tube, 2 black wires from wire harness connect to 1 connector bolted to engine block. Removed, cleaned, looks ok.

Power Distribution Center
Pulled all fuses and checked, all check ok.

Fuel Pump Sound.
Turned key to second position and can not hear fuel pump running, but I don't recall ever hearing it before but perhaps I just didn't notice. Is fuel pump dead or is something causing it to not get power?

Injector Manifold Port.
While having someone crank engine I repressed the valve, no fuel came out.

I still do not know why I am not getting spark from distributor or coil when I connect plug wire and press plug against one of the head studs on exhaust side of head.

I have something else I will toss into the mix. I have an aftermarket Keyless Entry/Remote Starter/Security System that was in the jeep when I bought it about 5 years ago.
Several months ago I had an issue where the horn started beeping and would not turn off with the keyless entry then the doors kept trying to lock and unlock while the parking lights kept flashing.

Is there a possibility the security system has failed and is preventing spark and gas?

Jimbo Slice

Yes.

BlueRidgeMark

Spark & fuel absent = check ASD function.

NCDON

Yes, meaning it is acceptable to test CPS by jumping B-C connectors at the harness side of plug to confirm CPS?

NCDON

I just swapped the starter relay with the AST relay, still no start. Strange thing when I stopped cranking the engine, the horn beeped 3 times?

Jimbo Slice

Yes as in, it's possible your security system is messing with you.

NCDON

If it is security system related I do not have any idea where to start removing the under dash wiring to bring things back to pre security days...

NCDON

I just spent the last hour or so under the steering wheel area, this aftermarket keyless entry, security system looks as though it was installed by drunken monkeys. It appears the system consists of 2 black boxes and 3 relays and is a very a amateurish installation using lots of electrical tape and tie straps.

I really don't want to start an attempt to remove this thing without exhausting other possible causes of lack of spark and fuel, my fear is I could create another problem.

One additional symptom I don't think I mentioned previously, my dash gauges are not working, all pointing to the left? Dash lights do work.

BlueRidgeMark

Typical alarm installers. They don't know and don't care about workmanship. They get paid by the job, not the hour. Slap it in, NEXT!

That's probably wise, but....

This points even more strongly to the drunken monkeys.

Take notes and pictures! Document what's there BEFORE you take anything apart.

I have a 97 FSM (Field Service Manual - the actual Chrysler shop manual) in PDF, so I can help out with wiring diagrams. Better yet, you can get one here. That will be easier than having me look things up for you.

But we are here for any questions you have.