Who knows WJ Grand Cherokees?

I am going to start of by saying that I don't care about your Chrysler/Jeep hate, so leave those thoughts to yourself. Thanks.

That being said....

I will be "acquiring" my BIL's 2001 WJ Laredo. It is currently experiencing electrical issues and he's had several things replaced. However he tells me after one thing gets replaced, two weeks later something else dies.

To me is sounds like something related to the BCM. His turn signals don't work, the AC doesn't work, and random things have stopped working.

He did mention that the PCM took a dump and he had the mechanic replaced it and it's run fine after that.

Any suggestions where to start? It's been a really reliable rig and this all started in the last 6 months. Bad BCM? Bad wiring harness?

I'd be looking at the BCM and the harness. Is there any chance that this has been in a flood?

Naw, it's just a Jeep thing from that era. They are known for wires breaking in the door harness, particularly the left front. The BCM gets its little brain scrambled by all the random FUBAR signals it receives so it does stupid stuff. Usually the first complaint is the door locks and power windows work intermittently. Do the below before condemning the BCM:

Remove the driver's door panel and the kick panel. You'll see the harness snaking through a rubber bellows, disconnect it from the door end of things and pull it inside the car. Look in the area that went inside the rubber tube, you will quite often find a wire broken inside the insulation. Don't splice it straight back together because that won't last. Splice in a section about 10" long that begins and ends OUTSIDE that rubber bellows tube thingy. The worst offender was a black ground wire that was larger gauge than the rest, making it easier to break. Some of my guys would replace that one large wire with three smaller ones, the theory being the smaller gauge wire was more flexible thus less likely to break again.

You occasionally see this happen with the right front door and I never saw it happen with a rear door.

In reply to Curmudgeon:

Thanks, that sounds like the place to start.

DrBoost - no it hasn't been in a flood.

If I remember correctly, there is a vacuum line under the battery that tends to go bad and that will cause the AC and the cruise control to not work. Door locks and windows not working is usually that wire harness in the door. Also, the wire harness in the engine bay tends to go bad very often. Jeep tended to run the wires near very hot parts of the engine and not protect them properly. The solders in the BCM go bad often also. If it's having start issues then check the camshaft and crankshaft position sensors first.

In reply to jrflying:

Ok thanks for that as well. It's a 4.0L, so would it have crank and cam sensors?

I imagine it won't take much to fix, it will just be time consuming.

Yes the vacuum line routed under the battery box will get eaten by acid and kill the manual A/C and cruise, both of which are vacuum operated. That's about all I ever saw go wrong with the manual A/C.

OTOH, the ATC dual zone systems have a whole different host of issues related to breaking/broken blend doors which are a pricey bitch to fix.

The 4.0 engines have a cylinder head bolt with a stud that sticks up on the left rear of the engine. The engine harness rubs right on that stud, vibration will cause the harness to get chewed up and lead to weirdness.

Yea the 4.0 has both sensors. If you replace the camshaft sensor, take a look at the cam shaft sychronizer also. I have heard of the gears at the bottom starting to fail and will drop some metal on your camshaft.

Here is a pretty good write up with some tricks for the Crank sensor. You will replace it at some point in the Jeeps life. It can be a pain in the tuckus:

CPS change

Thanks, hopefully all this info will come to use.

Thanks Curmudgeon. I'm living with one of these. It's on the second BCM - first was replaced in the first couple of years of ownership. It's doing oddball things that are obviously wiring related, I'll check those door wires.

In cool weather, the turn indicator stalk will just buzz when you indicate a right turn. But it'll get better when heat gets into the interior. One of the rear brake lights goes out, and when it does the buttons on the ceiling mounted computer stop responding. I really really want this thing to leave, but Janel loves it.

In reply to Keith Tanner:

This WJ I'm getting also has the brake light issue.

Who knew Land Rover and Jeep collaborated?

The brake light issue is often bad contacts on the taillight bulb sockets where they connect with the housing. Try bending them out a bit to get contact again.

On my '02 I made new battery cables out of heavier wire with better terminal ends. This solved a slow start issue and other electrical weirdness related to corroded cables.

I also had the automatic headlights malfunction and randomly turn the lights on when parked. A new turn signal stalk solved the problem but you could just not use the auto headlight feature.

Yeah, I've been working with the sockets.

Oh, it's also now refusing to start when cold unless you turn on the ignition and wait a few seconds. I'm blaming this on the fuel pump getting tired.

Dropping the tank isn't the worst job in the world unless you're in the rust belt. Same goes for the fuel filter located above the rear axle on the driver's side. It can be a real pain to disconnect the fuel lines if you can't clean out the connectors.

The EVAP system can cause check engine lights but it's usually just cracked hoses or a bad solenoid.

99-early '02 4.0s have the 331 head which develops a crack between #3 & 4. V8s will drop the valve seats if you overheat them since they are pressed and not staked into the aluminum heads.

Curmudgeon wrote: Naw, it's just a Jeep thing from that era. They are known for wires breaking in the door harness, particularly the left front.

Pretty much this. At least its an '01 & not a '00. The '01's (for the most part) had the updated brake calipers so you won't chew through rotors & squeak all the time. Also, you will most likely good really good at replacing the door lock actuators. Not that I'd know or anything (lol)

e46potenza wrote:

Curmudgeon wrote: Naw, it's just a Jeep thing from that era. They are known for wires breaking in the door harness, particularly the left front.

Pretty much this. At least its an '01 & not a '00. The '01's (for the most part) had the updated brake calipers so you won't chew through rotors & squeak all the time. Also, you will most likely good really good at replacing the door lock actuators. Not that I'd know or anything (lol)

I thought the Akebono/Teves switchover was a running change on 2002 MY trucks.

Never slam a door, not even a little. Close them gently unless you want to buy a new window regulator.

All I know is they're the last of the capable jeeps with a roof, I know for a fact you can ford 30" of water in one and come out with everything bone dry.

What I know is that this one is the Laredo Sport with the special appearance package which has 17" wheels and leather interior. It may have a sunroof, I forget.

My mother and I must've had the only two that were fairly reliable. Ours both had their share of issues(mine from PO's not taking care of it, my mother's from the calipers/regulators), but overall, they were very enjoyable, reliable vehicles. I regret selling mine almost everyday. My sister is still driving my mother's(who was the original owner-2001), and about to drive it from Phoenix to Virginia to move. I drove mine all over the western part of the states: Colorado, Wyoming, Utah, Arizona, basically everywhere but Nevada and California. I took it to and from Colorado to Ohio a couple times. Basic maintenance is key with these, and using proper parts/improvements on original designs. 75-80% of the issues on these are ill-maintained owner issues. Sometimes, you just get a crap one. Happens with any used car. My Limited 4.7 with Quadratrac was nearly unstoppable.

That being said, I would NOT touch one with electrical issues. They're extremely complicated electronically and not easy to fix.

Ours is reliable enough, it's just got enough foibles to make me really nervous. Nothing important has ever happened to it. Once the stock rotors were replaced with Brembo blanks, the wear issues went away there.

Mine is an early '02 with the older head and it originally had the Teves calipers like this.

But when I swapped my open differential axles for Quadradrive axles the new one had Akebonos on it. They have much better feel and stopping power. More importantly the pistons don't stick and cause warped rotors.

Now my 4.0 WJ has a Selec-Trac transfer case with Quadradrive front and rear axles. The front on all WJs is a D30 but the rear is an aluminum D44 on V8s. Straight swap on mine but some have needed to shorten the rear driveshaft.

In reply to bluesideup:

I didn't know that about the brakes. Good to know!