[craiger28]

Hello. I am new to this forum. I have 2 97 Grand Cherokee's laredo that will not start but crank all day long. One will start and then turn off again after about 2/3 seconds of running. First thing I thought was fuel, both have about 50 psi at the rail. Next coil, both have been changed with new ones. One was running fine and the other one wasn't so I started to change parts from one to the other trying to solve the mystery. Now both won't start. Can you do damage to the ECU by changing it back and forth? They are the same part numbers. Any suggetstions? other parts tested and changed: IAC, TPS, CPS, Dizzy, and still nothing. I tried other tricks with the key since I had the battery unhooked, but that didn't work either. I really need some techy help on this issue.

Thanks.

[newfieZJ]

have you changed the ASD(auto shut down) relay , if not , switch it for the AC relay and try it .

You changed with new , or just swapped CPS`s , maybe both are bad ? What did you do to test these ?

No harm switching parts like sensors off the same yr jeep .

The one that runs for a few secs sounds like a sercurity issue , try locking-unlocking the hatch and both frt doors to disable it

Check all your fuses carefully , then check to see what has power with the key ahead (multi-meter)

[craiger28]

I tried the ASD by switching the A/C Relay (the A/C was working by the way) and it still just turns over. The car that runs for 2/3 seconds does the same thing with either ecu in it. Is there a way to check the ecu in these trucks? I tried the security thing too, By locking and unlocking all the doors and hatch over and over again. Still does not want to run. Is there a way I can find out what should be lit up when the key is turned forward with a test light?

[nashmd454]

I first would have mentioned spark...like in coil...btu after reading the whole thing...it is weird how you have 2 with the same prob / or one that runs all of 2-3 secs.

[-Joe-]

Did you check for engine codes? It might lead to something stupid..

You can take it somewhere which might be hard since they are not running, get an OBD-II scanner or do it yourself via:

To display codes cycle the ignition key On-Off-On-Off-On within three seconds. Count the number of flashes, first digit, pause then second digit will be displayed in a series of flashes. (2 flashes, pause, 1 flash = 21)

11 - No Crank Reference Signal At PCM (Crankshaft Position Sensor)
12 - Battery Disconnected Within last 50 Key-on cycles
13 - No Change In MAP Sensor
14 - MAP Voltage Too Low Or Too High
15 - No Vehicle Speed Sensor Signal
17 - Engine Is Cold Too Long
21 - O2 Sensor Signal At Center Or Signal Shorted To Voltage
22 - ECT Sensor Voltage Too Low Or Too High (ECT = Engine Coolant Sensor)
23 - Charge Air Temperature Sensor Voltage Too High Or Low (Intake Air Temp Sensor)
24 - Throttle Position Sensor Voltage Too High Or Too Low
25 - Idle Air Control Motor Circuit Shorted
27 - Injector Control Circuit Signal Not Responding Correctly.
31 - EVAP Purge Solenoid Circuit Open Or Shorted
32 - EGR System Failure
33 - A/C Clutch Relay Circuit Open Or Shorted
34 - Speed Control Solenoid Ciruit Open Or Shorted (Vacuum Or Vent)
37 - Torque Converter Clutch Solenoid Circuit Open Or Shorted
41 - Generator Field Not Switching Properly
42 - Auto Shutdown Relay Control Circuit Open Or Shorted Or No ASD Voltage
44 - Battery Temp Sensor Voltage Out Of Limit
45 - Overdrive Solenoid Circuit Open Or Shorted
46 - Charging System Voltage Too High
47 - Charging SYstem Voltage Too Low
51 - O2 Sensor Signal Stays Below Center (Lean)
52 - O2 Sensor Signal Stays Above Center (Rich)
53 - Internal PCM Failure
54 - Sync Pick-Up Signal Not Detected (Camshaft Position Sensor/Ignition Pickup)
62 - PCM Failure SRI Miles Not Stored
63 - PCM Failure EEProm Write Denied

55 End Of Codes

[craiger28]

Joe, great suggestion. I have no engine light on but I remember that my old Dodge caravan I could do the on off on off on trick and get the two digit codes from it, I completely forgot about that. So anyway I did it and got 12 and then 55. The battery was disconnected while I changed the ecu so what now? BTW, I do have spark at the plugs.

[-Joe-]

Disable the alarm by grounding that yellow or purple wire.. forget which.. that way you know thats not the problem.

Someone will say how.. Theres a thread on disabling it somewhere on here.

[craiger28]

Joe, I looked for it and read some threads but no luck finding anything about a yellow or purple wire. Can you help me further. Both WJ's have the same exact codes: 12 then 55. So it makes sense since I had the battery unhooked on both of them. Thanks.

[-Joe-]

Originally Posted by craiger28

Joe, I looked for it and read some threads but no luck finding anything about a yellow or purple wire. Can you help me further. Both WJ's have the same exact codes: 12 then 55. So it makes sense since I had the battery unhooked on both of them. Thanks.

ZJs..not WJs..

12, 55 are normal.. 12 will always show up regardless of how long the battery was messed with.

This is for earlier years ZJs but wouldnt hurt to check to see if the wiring is the same.

http://www.jeepforum.com/forum/f13/how-disable-your-alarm-your-zj-483020/?highlight=disable+alarm

It would at least insure that the alarm is not the problem, so you can move on to other stuff.


Have you replaced both the Crankshaft position sensor and Camshaft position sensor? (ignition pickup, under the dist-cap)

Another link for no start issues:

http://autorepair.about.com/library/a/1h/bl651h.htm

[craiger28]

So I have a ZJ, all this time I thought my 97 GC Laredo was a WJ? If a 12 code is normal to have I am screwed. I thought the 12 code made sense since I disconnected the battery on both of them and now they will not start. I have been told it could be the alarm needs to be disarmed. I have tried the key in the locks and hatch trick, now I see that I need to ground the Purple wire. I have replaced the CPS and othe CPS (pick up module in the dizzy) already. Is there a quick way to ground the alarm sysytem just to get it started????

[srxj95]

kinda the same thing happened to my buddy his asd fuse blew i would check that hes got a spare pcm if u figure out thats the problem let me know its a 97 tsi pcm california emissions got the letter d on the end of the pcm number he ended up putting a letter c pcm in and it worked fine

[-Joe-]

Originally Posted by craiger28

So I have a ZJ, all this time I thought my 97 GC Laredo was a WJ? If a 12 code is normal to have I am screwed. I thought the 12 code made sense since I disconnected the battery on both of them and now they will not start. I have been told it could be the alarm needs to be disarmed. I have tried the key in the locks and hatch trick, now I see that I need to ground the Purple wire. I have replaced the CPS and othe CPS (pick up module in the dizzy) already. Is there a quick way to ground the alarm sysytem just to get it started????

Everytime that I have checked codes I get 12. Its just there and does not go way.

1993-1998 are ZJs

I posted a link to how to ground it.

[craiger28]

Originally Posted by -Joe-

Everytime that I have checked codes I get 12. Its just there and does not go way.

1993-1998 are ZJs

I posted a link to how to ground it.

Joe, grounding it is not a good idea! All it did for me was make my battery go dead.