dasgib

Greetings from Down Under.

Firstly can I say what a fantastic forum this is. The level of technical knowledge is amazing, and the helpfull "community spirit" is very heart warming indeed.

Secondly, I have a problem and I'm hoping someone may be able to help.

A neighbor of mine has a '98 XJ Cherokee "Sport" that was towed to my place a couple of days ago after it refused to re-start after he filled up with petrol (or gas). Upon arriving here a quick check revealed it has no ignition spark.

A more detailed inspection revealed that it has a problem with power going to the ignition coil in that the moment the key is turned to "on" the coil briefly receives 12 volts before it drops to nothing after less than a second and it never comes back. Cranking the engine shows that the coil doesn't receive more than .15 volts of power, and the engine obviously won't start.

The car is a 4 litre 6 cylinder with an automatic transmision, and I have a repair manual for this model. I've tested the camshaft position sensor and automatic shutdown relay which I thought might be the problem but they both report to be okay according to the manual.

I plugged an OBD-11 scanner into the car and it reported the following:

1281 - Coolant temp too low
0320 - No crank reference signal at PCM
0463 - Fuel level sending volts too high
1685 - SKIM invalid key
1491 - Radiator fan control relay circuit

Of those, the only two that give me cause for concern are the no crank reference signal and the SKIM invalid key as possible reasons why the car won't fire, and while I haven't checked either as yet they're my first port of call tomorrow morning.

Basically, what I wanted to ask is if anyone can think of anything else I should be checking, or has had a similar problem and found a solution they could share I'd be very thankful indeed.

Thanks in advance, and congratulations on you, the users, making this such a great forum,

Regards,
George.

daniele70

Hello I certianly know what you are going threw. Well you need to check if your crank sensor is working. This is done be getting a volt meter and setting it on ohms. Measure the reading while your friend is trying to start the engine. Make sure you pull the fuel relay so you dont dump fuel on your pistons. If you have a hayes manuel it helps but if not then just if you have a round plug that contects the sensor to the bell housing on the transmission. Mine was located on the upper drivers side. Put your ground wire on the middle plug and the postive lead in one of the other ones. You should see some kind of reading. The book says measure between B and C and you should read not read anything. But I can tell you one mine there was no B and C marked on the inside of the plug. From the middle pin that should be B and one of the others while turning over the engine you should see a your meter changing reading. This is because as the flywheel is turning the magnet field on the sensor is changing which gives your a different reading. If this happens then your sensor is good. If not then replace it.

w_huisman

If someone has it available, I would like to know the part number of the crank sensor.

If someone has any other recommendations on possible causes for this no-fire symptom, I'd appreciate hearing them as well.

I'm going through the exact same thing with my truck right now. It's a 97 Cherokee sport with the 4.0.

TIA!

BuckB91XJ

dasgib, X 2 on the CPS. It sounds to me like you have a bad (CPS). Crank Position Sensor. When it goes bad you have no Spark, Spark timing and no Fuel injector pulse.

xjbones

x3 on cps. sometimes you can jerk on the cps wires while someone is cranking it over and it will start. if it starts, you know its the cps for sure. im pretty sure the pcm only looks for crank position in start ups. someone will correct me if im wrong

daniele70

Its true the the CPS along with the Cam position sensor is used to fire the sparkplugs. If you loose the Crank sensor your engine will die. but if you loose the cam sensor then when you shut it off it will not start. If you do have one. I know that some older jeeps have the distributer and some have the sensor under the points of the distributer.

If you have a coil pack to fire your spark plugs you have a four wire plug you can measure the primary side to see if you have resistance. Sometimes these go bad but not to often.
Also you can jump out the Auto shut down relay and see if that is not letting you get the voltage needed.

dasgib

Hi everyone,

Thanks for the helpful replies, they've been great.

Unfortunately, a new CPS hasn't fixed the problem, and the car is still stuck here unable to start. Things are starting to get desperate now as the owner wants his car back, I want it out of my driveway and I have no idea what's wrong with it

So far, I've done the following:

Replaced the CPS.
Tested the cam position sensor which reports as being good according to the test procedure outlined in the factory manual.
Replaced the Automatic shutdown relay.

The problem is still the same in that when the ignition is turned on the automatic shutdown & fuel pump relays are energised for approximately 1 second before they both switch off again. During that time the ignition coil receives 12 volts it drops to nothing as the ASD shuts down. Cranking the engine sees the coil voltage go from zero to .15 volts which is obviously not enough to fire the ignition system.

My understanding is that the Powertrain Contol Module controls the ignition system by grounding the coil's negative feed to fire the plugs, but this apparently isn't happening. I've wired the positive side of the coil directly to the battery to by-pass the ASD side of things but the PCM still won't ground the coil and fire the ignition system.

Everything on the vehicle that I'm able to test reports to be good, and I'm at a loss to explain why it won't start. All the wiring between the various components has been checked and the continuity is good, earth points are fine and there is nothing obvious that sticks it's hand up looking like the culprit.

The only possible thing I can think of that *may* be a problem is the immobiliser, but according to the manual if that's preventing the engine from running it should at least start for a second or two and then shut down if it's not happy whereas this thing has absolutely no spark whatsoever.

It's incredibly frustrating as I'm trying to avoid my good friend having to take the vehicle to a Jeep dealer, as in this part of the world dealer service charges are horrendously expensive and it could end up costing him thousands of dollars and he simply doesn't have the capacity to afford being ripped off.

For the record, the vehicle is a 4th month of 1998 build Cherokee "Sport" with the 4 litre 6 and an automatic transmission. I've been told by some people that it's a "series II" XJ by some people, and it has a tag inside the right front door saying "Manufactured for Export".

I don't know how much the Cherokee we got here in Australia differed from the American version, but the factoru repair manual I have was printed in the United States and it seems to be fairly relevant with some minor differences.

I appreciate anyone taking the time to read this rant, and if there's anyone out there who could offer any suggestions that may lead to getting the thing running I cannot begin to tell you how grateful we would both be.

Thanks in advance,

Regards,
George.

huntingman2706217

Is the distributor itself getting a signal from the ignition switch to say "turn on"? only other things i can think of it being is the ECM, distributor, or coil... Im not sure if the 96's have a ballaster and i dont know much about what they do but i think they do something with the ignition setup... i think newer model vehicles swapped to the resistance being made into the wire to the distributor... sorry i couldnt be much more help... around here these parts are cheaper so i just swap them out cheapest to most expensive instead of shooting wires and all that mess... lol

captainwoot

I'm am curious, here in canada the xj didn't recieve the skim key untill mid 2000/and 01. do you have a grey head ignition key? if the vehicle is equipped with the imobilizer and you do not have the correct key it will never start. If in fact it is equipped with the skim system you need to get your hands on a DRBIII scan tool to acess the skim module. When you turn the key on is ther a red or yellow security light that comes on?

Another option is to get a pcm from a nom skim vehicle, unplug skim module , install pcm and start.

if you can pm me the vin(last 9 digits) i can tell you if it is equipped with skim system

Willys55

Correct, you beat me to it. P1685 was the code to go after. get the right key and it will start. Imoblizer has shut it down.

dasgib

Hi Captainwoot, thanks for your reply.

The vehicle does indeed have a grey headed ignition key, and it also has the yellow "key" symbol on the dash that lights up when you first turn on the ignition which according to the workshop manual I have suggests that it's fitted with a SKIM system.

The owner has had this vehicle for some 7 years or so and it's performed faultlessly in that time according to him. He did originally have a spare grey head key but missplaced it some time ago and has has never found it. However the car has been working just fine up until a couple of days ago with the sole remaining key.

The problem arose a few days ago when he drove the car to his local gas station to fill up. He apparently stopped the car, filled the tank and when he got back in it refused to start. Up until that point it had no problens but it hasn't even looked like firing since then and remains here with no spark.

It's rapidly becoming a royal pain in the backside as I'm trying to get the car sorted for him so he can get to work on Monday morning, I've got other things I need to do before I go back to work on Monday and it's already Saturday afternoon and I'm no further along with it than I was two days ago.

Just to touch on your idea of fitting a pcm from non SKIM equipped vehicle, that sounds like an interesting option but I was told by someone local to me who is more familiar with Jeeps than I am that the PCM's are individually coded to each vehicle and fitting another unit won't allow it to start until it's been reprogrammed by a dealer with a DRB scantool.

I don't know if this is actually true, but if what you're saying is possible then I'd be willing to give it a try as the owner couldn't care less if the car has a working immobiliser or not.

Would it simply be a matter of swapping the PCM's and disconnecting the SKIM module as you say, or would there be anything else that would need to be done?

Thanks again for the help. It's comforting to be able to bounce ideas of people who are so generous with their time.

Regards,
George.

9XJSPORT7

Im at a loss to try and help here. Its possible that the skim module went bad. I dont about the jeeps as mine doesnt have it however my ford has the same type of system on it and when the system fails the car will not start. I also know that they can go bad with no warning. Might be something else to look into. Hope that helps

captainwoot

Yes if you can get a non skim pcm 1) disconnect batt 2) disconnect skim module 3) install non skim pcm 4) reconnect batt. this will work as long as it is not a new pcm (they come with no brains lol and need to be programmed)
I have done this with other chrysler group vehicles.
Good luck

captainwoot

I had another thought for you before you go searching for a pcm. check the connection at the skim module,
IMMOBILIZER MODULE - BLACK 6-WAYCAVCIRCUITFUNCTION1D1 20VT/BRCCD BUS(+)2D2 20WT/BKCCD BUS(-)3Z2 20BK/LGGROUND4F87 20WT/BKFUSED IGNITION SWITCH OUTPUT (ST-RUN)5Z2 20BK/LGGROUND6F1 20DB/GYFUSED B(+)
check for B+, key power and ground (the module is located in the column , at ignition switch)

dasgib

Hi everyone,

Well, it's currently 9:53pm on Saturday night, I've just packed up my tools after a long day and thought I'd pop in here with a follow up to my tale of woe about this Cherokee that won't start.

Sadly, it still won't start

I think I've tried every possible thing imaginable at least three times over the last three days, and not only can't I get the thing running but I still have no idea as to exactly what's wrong with the vehicle. Everything that I'm able to test checks out to be okay, yet it still has no spark and sits there looking very sad and sorry for itself.

It's somewhat embarrassing as a mechanic of some 30 years experience to tell my friend that I'm unable to fix his car, but I've simply run out of options and it'll now have to be hauled off to the local dealer on Monday morning.

Still, I'd like to offer my sincere thanks to all those who offered helpful advice, and there's some icy cold beer on the workbench here for you all that I shall drink in your absence

Thanks again guys. It's been a great comfort to know that there are still people out there who are willing to go out of their way to help a stranger.

Regards,
George.