93 XJ WILL NOT START! Please help ASAP!! Dead in Parking Lot!

Hey Guys,

This is my 1st post on , I am a regular on JU and Off-road.com. I think that I have officially stumped them there, so I would like to see if you guys have any ideas as to why my 93 XJ will not start, Here goes:

Backround: 93 XJ, 4.0 HO, Auto, 231.

I was all happy yesterday, ready to go camping. I replaced my H20 pump, Thermostat, cap and rotor, and rear u-bolts, and I was ready to go camping. On the drive to where I was meeting my buddy, I realized that the temp was still kinda high, and the electic fan was kicking on REAL late. So no worries I though, I stopped at Auto zone, bought some wire, a fuse link, and a switch to wire the fan to a switch real quick. So (I'm not sure where my head was here) I unplugged the temp sensor from the thermostat, and then stuck the wire in one pin, and the other end to the battery, fan didn't come on. I stuck it in the other pin, fan didn't come on, then I tried both pins at once, fan didn't come on. I then realized that I was retarded and tapped into the white wire on the electric fan, and the fan came on just fine. I sloppily wire the switch in, and was ready to go! I got in the Jeep, started it, and NADA!!! The Jeep cranks, and sound COMPLETELY normal, but will not start, it turns, the started is fine, there is gas in the tank. I have never, ever, had this thing not start before. I though it might be the new cap and rotor, so I took that off, inspected it, looked fine. I checked all the plug wires, all tight. I took one of the wires off the plug, shoved a screw driver in there and had my GF crank it, no spark arching to the compressor, or valve cover.....That's weird. I unplugged the fuel line (in) and there was gas leaking from the rail, has GF crank it, and I got a little squirt, but nothing much, or as much as you would expect. I unplugged the out line, and nothing coming out of the line, or leaking from the rail. I hammered the starter, I hammered the gas tank, I tried starting fluid, all did nothing. I checked every single fuse, under the hood, and in the cabin. I swapped all the relay's around, and tested that all, all worked, and no fuses blown. I finally killed the battery trying to start it so much, so that is when I gave up, and it has been sitting at Autozone ever since.

Why would I not get any gas, or that much coming from the fuel line when my GF tried to crank it? that's not normal right? Why is there no spark arching when we crank it with the screw driver in there, and hold it up to metal? That's not normal either. And how did this all result from me trying to wire the electric fan? What did I do wrong, minus trying to get the fan come on from tapping into the thermostat sensor? Surely by doing that it would'nt have caused this right? I am really stumpped here.

Please guys, I am really desperate here, I need some help, and I need it quick, WTF is wrong with the jeep? I really need to get this fixed, any help would be great.

Thanks,

Todd






LOTSA MODS, LITTLE MONEY!
1993 Cherokee Country, 35" Trxus, 8.8 rear, 4.10's, AJ's Custom Bumpers.

Well here's an update. I spend the last 4 hours at autozone fawking with this thing trying to get it to start. I have narrow this down to not having any spark at all. I replaced the CPS, I replaced the cap and rotor (again) I replaced the ignition coil, I replaced the coolant sensor at the thermostat, still nothing. I plugged all the sensor plugs, cleaned em, and they re-plugged them in, nothing.

One more thing that I did notice is that only the HI setting on my fan works now, this was not the case before all this happend. I had it on low when I stopped to run into autozone, now only HI works.

I have some codes:

12
44
14

In that order.

12, I i dunno what that is, it's not in the FSM,

44 is "Displays battery temp sensor volts out of limit" Condition: powertrain control module failure

14 is "MAP Voltage is too low" Condition: MAP sensor input less than acceptable voltage.

So what should I start with? The MAP or should I replace the whole freaking PCM? I'm at a loss guys. PLEASE HELP. I don't wanna replace the PCM!!

Thanks,

Todd

Replace the MAP sensor. A fried MAP sensor will cause a no start condition (it's the only sensor that'll cause a no start other than the CPS). Your PCM is throwing up codes so it's obviously doing its job.

I will replace that tomorrow. If the PCM is in fact working, why am I getting the code 14 (well obviously cause of the MAP) but why is it saying "condition, PCM failure" in the FSM?

Todd

A Littel update. I still have ZERO spark. I check all the fuses for continuity, and they all check out. I back probed the camshaft (CAMSHAFT) position sensor, and I am getting a fluxuating voltage of .41 to .62 while cranking (not sure what this means) I backprobed the coolant temp sensor, and I am getting voltage there as well (not sure what to look for)

I unplugged the PCM for 5 minutes, and now I don't have code 14 anymore, just 44. I am still getting fuel. I ordered a MAP, Coolant Temp Sensor, and IAT today, will try those tomorrow night.

Does anyone know how to test the: Coolant Temp Sensor, IAC, MAP, Camshaft Poistion Sensor? Also I couldn'r reach today without getting real dirty (work clothes) but when I do backprobe the connector for ignition coil, what am I looking for.

Thanks!

Todd

This is an overly obvious question, but you didnt spin the dizzy cap 180 degrees when you replaced it did you?

I've got an older XJ so I'm not much help with your codes. I did a little research and Code 12 is just the first code to identify the start of the codes... http://www.all-parts.com/diagnostics/mechanics/Jeep_Cherokee.html

1997 Jeep Cherokee
All Part Groups Other When driving Always

Q: The "Check Engine" light is on. The codes are 12, 31 & 55.

A: The 12 is the start reference code. The 55 is the end reference code. Both mean nothing which leaves you with the 31 code. Match that one and it will tell you which part in the system may have a problem. Ed

A couple of questions for ya too. When you turn the ignition to the on position does the fuel pump come on? I can always hear mine.

Is it possible that by wiring into the CTS you may have sent a voltage spike back to the PCU that cooked something? Just a guess. If all else fails maybe removing the PCU and having it tested by a shop or the stealership might at least rule that out.

Good luck and I hope you're up and running soon.

Cap is on correctly, and yes my fuel pump is loud and clear. My parts are in and I will tackle those after work today. If they don't work then out comes the PCM and I'll have that tested for shorts. I was really worried about replacing that, but a new on is only $150, so I suppose it could be a lot worse. I'll let you know what happens.

Todd

Replaced MAP today, I have the recommended 5v at that connection. My BLK/ LT BLU wire at pin 4 on the PCM is getting a good connection as well. IT STILL HAS NO SPARK!!!

Can anyone help, I have entered desperate stage.

Todd

Hey,

I looked around a little bit and founds this article for a Dodge Ram. I suppose the two have similiar electricals or at least it may provide some info on your fault code. It looks like code 44 is a drivability issue as the battery temp sensor info tells the electrical system how much power is needed. Not super helpfull but here, for what it's worth:

http://www.dodgeram.org/tech/gas/Trouble/Fault-44.htm

You're still getting this code right?

Thanks for the reply, i actually do not have 44 anymore, just 14, which would not cause the Jeep to not start. I think that the problem is either the PCM, or (despite testing them) a relay somewhere. My parts did not come in yesterday, so I'll be installed the above mentioned sensors tonight. If that fails I'll have it towed to jeep so some experts can diagnose it. I just didn't budget for this, and have been saving for a starter bike, that's over now =)

Thanks,

Todd

FWIW, my money's on the PCM... Just a WAG though. Good luck, sorry about your troubles.

I unplugged the temp sensor from the thermostat, and then stuck the wire in one pin, and the other end to the battery, fan didn't come on. I stuck it in the other pin, fan didn't come on, then I tried both pins at once, fan didn't come on.

Click to expand...

Dude, plain and simple: You fried your PCM.

By applying 12v to the coolant sensor circuit, you damaged the PCM.

It's not a good thing to be poking around with 12v on sensors.

Only a couple more of the obvious things:

- I picked up a cap and rotor set from AutoZone and the rotor (while correct for the set) did not fit my distributor. The original rotor had a long tab (never seen anything like it) to engage into the distributor cap. The replacement did not and the AutoZone guys tried to convince me it would be OK. Are you sure that you got the right rotor? do you still have the original??

- How old are your wires? When you pulled the wires off the old distributor cap maybe one of the wires failed. Why not try and replace the coil to distributor lead wire. BTW a basic wire continuity test may show OK but then may fail under load.

- You didn't mention if you had removed your hokey fan switch and wiring before doing all this testing....

good luck

Mark

BTW the blower on HI may be a red herring.

There's a blower motor resistor pack under the passengers dash. If this fails, the blower will only work on high. It may be another pointer to an electrical problem (rather than rotor/wires) or the blower motor resistor pack may have just decided to give up at the same time.

I also took a look through my Haynes manual: and theres a note about fusible links:

"some circuits are protected by fusible links: these links are used in circuits not normally fused... Although fusible links appear to be heavier guage than the wire they protect, the appearance is due to thick insulation. ...Fusible links cannot be repaired but a new link of the same size wire can be put in its place" (Pg 12-3 of the Haynes Jeep Cherokee Repair Manual)

I have no idea what a fusible link look like, or whether Jeeps have them but it is another possibility

Mark

Digger87xj said:

Dude, plain and simple: You fried your PCM.

By applying 12v to the coolant sensor circuit, you damaged the PCM.

It's not a good thing to be poking around with 12v on sensors.

Click to expand...

I fear you may be right.

Digger87xj said:

Dude, plain and simple: You fried your PCM.

By applying 12v to the coolant sensor circuit, you damaged the PCM.

It's not a good thing to be poking around with 12v on sensors.

Click to expand...

guaran-damn-tee it...
the computers actually ground the fan so when 12volts gets shot straight into it with no resistance, it fizzles out...
btw saw this post on pirate other day but i couldn't get logged on to reply...

Thanks for all the reply's guys. A new PCM is on order, and I should have that in the next couple of days. The cap and rotor BTW are identical, and I did put my original one one aswell, just to test, and still no spark. The PCM cost me $212, since in needed the expensive one, and not the cheap one ($155)

I just feel so freaking stupid that I even did this, I think that I had such a hard on to go camping that I wasn't thinking. Oh well, live and learn. I'll post back after the PCM goes in.

Thanks!

Todd

well was it the PCM or what?

yes it was, replaced the PCM and it fired right up. 1 week later, I blew the #6 rod, currently building a 4.7L =)