2002 Grand Cherokee Laredo crazy problems - JeepForum.com
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post #1 of 22 Old 01-29-2020, 08:11 PM Thread Starter
2002laredo
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2002 Grand Cherokee Laredo crazy problems

Hello,
I have a 2002 Grand Cherokee Laredo 4X4 with 206,000 miles.
I bought it not running with no wiring harness attached
The former owner had problems with it and he brought it to the dealer
they swapped out the computer and it did not run after that ....then they told him there was a short in the wiring harness so he removed the wiring harness never checked for the short .....after I bought it I checked the wiring harness and there is no short anywhere.
He said they programmed the PCM to the VIN.... which I don't know how true that is.... because I know how dealers are, and never ran after that and he towed it back home and that was two years ago and I just bought it about 2 months ago.
I put the wiring harness back in and it ran terrible for about 30 seconds at a time had code p0201 only.
I checked the wires going all the way back to the PCM from injector 1 as well as the other injectors...it is not shorted , there are new injectors crank sensor cam sensor and I believe an oxygen sensor.
I put new plugs in it and it also came with a new coil that I put in and made no difference... So I put the original one back in. I put all new spark plugs in and changed the oil.
I found out basically the problem was the fuel pump so I had to cut a hole through the trunk to put one in because the tow hitche is welded to it and you can't drop the tank , now it starts right up and it runs and I now have 6 codes and this is crazy and I have no idea what is wrong with this Jeep
The codes are:
P0201
P0340
1388
743
1765
1495
I took the harness connectors off the transmission checked them sprayed them with electronics cleaner.
I took out all of the injectors and cleaned them with a battery and brake cleaner.
I have no idea what is wrong with this thing. I'm trying to sell it... if anyone knows how I can clear these codes and get this thing to run right please tell me .....thanks for your help

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post #2 of 22 Old 01-29-2020, 10:29 PM
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All six codes have to do with 12v supply or control circuits.... start with the basics. Do you have all the fuses and relays in BOTH fuse panels? Are the fuses all good, and do the relays have there corresponding 12v supply?(use wiring diagram and check which cavity should have power) Do all the relay cavitys have their corresponding grounds? I also wonder about the engine grounds being an issue, Uniblurb did an excellent write up on all ground locations on these Jeeps. It would be worth a look at.

'00LMTD-4.7l,242hd,D30,D44A,3.73's,True-trac front,Spartan rear,3"BBfront,2"BBrear,JK'sW/32's
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post #3 of 22 Old 01-30-2020, 03:47 AM
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Thanks Bigrigr and below is the ground write-up. Be sure and look at the photos at the end in the "Edit/addition" section especially if it's a 4.7. Never did say what engine engine it is? Good luck.

https://www.jeepforum.com/forum/f310...-info-4192594/

96 4.0 ZJ Laredo, 2004 4.7L WJ Limited, 96 4.0 XJ (son's)


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post #4 of 22 Old 01-30-2020, 07:36 AM
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Some thoughts


p0201 #1 inj circuit. There is NO corresponding misfire code (p0301) 2 thoughts check freeze frame and look at misfire counter BUT there was a TSB for this pointing at TPS, and that has me asking AIRBAG light?

P0340-NO CAM SIGNAL AT PCM - jeep does start? does your scanner graph wave forms- voltages?

P1388-AUTO SHUTDOWN RELAY CONTROL CIRCUIT these 3 are simplwe wiring cks
P1765-TRANS 12 VOLT SUPPLY RELAY CTRL CIRCUIT
P0743-TORQUE CONVERTER CLUTCH SOLENOID/TRANS RELAY CIRCUIT

P1495-LEAK DETECTION PUMP SOLENOID CIRCUIT behind L/R wheel check connector is there 12v KO?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #5 of 22 Old 01-30-2020, 08:04 AM
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If you’re using the original harness, since they may have previously had issues with it, it wouldn’t hurt to go through and wiggle parts of it and monitor for any small changes. Shorts can come and go.
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post #6 of 22 Old 01-30-2020, 10:54 AM
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you have not cleared up which engine?

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #7 of 22 Old 01-31-2020, 04:35 PM Thread Starter
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No I have never checked the inside fuse panel but as soon as I can I will pull every single fuse out one at a time and see if they are good I could not respond sooner than this because the way this website is designed I couldn't figure out how to respond to anyone I still don't know if I can even edit my original question it's just plain ridiculous the engine is a 4.0 6 cylinder.
Also the TPS does not click on and lock the plastic tabs are broke but it stays on very snuggly I'm thinking because of all of these random codes I may need a PCM but I'm not sure all of the fuses and relays on me under hood fuse panel seem to be okay
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post #8 of 22 Old 01-31-2020, 04:37 PM Thread Starter
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It starts and it will run with a miss.
The TPS sensor fits on snuggly but the plastic locking tabs are broke the engine is a 4.0 6 cylinder
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post #9 of 22 Old 01-31-2020, 04:38 PM Thread Starter
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I just figured out how to respond to someone that's why the delay.
I still don't know if there's a way to edit my original question so I can put the engine size in there..... but anyway the engine is a 4.0 6 cylinder
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post #10 of 22 Old 01-31-2020, 05:43 PM
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As long as the TPS connector isnt backed out, it shouldnt have anything to do with a misfire. We really need to see if you can narrow down which cylinders are misfiring. A good code scan tool with misfire diagnostics would be helpful here, but you could also do it the old school way and disconnect the coil connectors one by one and see which ones do NOT make a difference.(this will set misfire codes for each cylinder, if you dont already have them) If the cylinder is firing correctly, the engine will labor when you unplug the coils, if the unplugged coils doesnt make any difference in how the engine is running, then thats a cylinder to start diagnosing.

Really there are two or three of those codes you have that could make this thing run like crap on their own.... Im kinda surprised it even starts...

'00LMTD-4.7l,242hd,D30,D44A,3.73's,True-trac front,Spartan rear,3"BBfront,2"BBrear,JK'sW/32's
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post #11 of 22 Old 02-01-2020, 09:37 AM Thread Starter
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4.0 6 cylinder
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post #12 of 22 Old 02-01-2020, 10:26 AM
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A 4.0L - I gave some code info above, The misfire you feel would have me looking at cyl #1 as there is a p0201 code.

Your concern about TPSsnapping in - put anew sensor on shopping list, I woould feel comfortable with a aftermarket TPS.

I asked about AIRBAG light?

Lets try this - clear codes - removing neg cable will do.

When you are logged in, on the bottom of your post is the option EDIT. I suggest you just make a newpost as we may not reread the older post.
Attached Thumbnails
edit.jpg  

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #13 of 22 Old 02-01-2020, 10:38 AM
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I did not mention - how do plugs look?
wet, dry, black, tan, and you did use solid core plugs nothing fancy?
double chek the inj connectors esp on#1 these connectors often fail to make good contact.

I suggested the code reset so as to attempt a second look 2nd opinion so to speak.

There is NO remote starter on this jeep? advise.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #14 of 22 Old 02-02-2020, 10:55 AM Thread Starter
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I'm going to work on it in a few minutes I'm going to check all of the fuses on the interior fuse panel to see if any are blown and I'm going to check to make sure there was power going to the ASD relay which should be ok because the fuel pump comes on and it starts I just moved it and it runs terrible when it's cold will barely move but it runs since I put a new fuel pump in
Yes the airbag light is on
there is no remote starter and no security system.
The plugs are new I put them in.
the old plugs were all light colored with no oil no black carbon or anything they looked fine but I replaced them anyway because I thought that might be the problem...... they are just standard NGK plugs for this vehicle... don't remember .
what type.
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post #15 of 22 Old 02-02-2020, 11:32 AM Thread Starter
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TCM and ASD relays have power and ground all of the small fuses in the underhood as well as interior fuse blocks have power and are good except for fuse number 16 which says O2 sensor 15 amp which has 0.12 volts with key on. I cleaned the ground connections with a drill and a wire wheel so this Jeep is very well grounded.
The battery was disconnected for several days I just connected it started it up it just has code 0201 but the rest of the calls will probably pop up if I let it run long enough I checked the connector at the injector and it seems to be on type I wiggled it
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