Top 10 2003 Jeep Grand Cherokee Questions & Answers

My Answer:

It appears that very possibly you have a bad ABS wheel sensor either up front (right or left side) if you only have Disc Brakes in the front and drum brakes in the rear, or else a bad ABS sensor in one of the rear wheels with a 4 wheel Disc Brake system.

The damp part was the giveaway, as if it's doing it in dampness then surely it'll do it when wet as well. That is a given!

Esp if it's not doing it in DRY weather.

If it's not a bad (leaky as from moisture getting inside it) ABS wheel sensor then it could just be chaffed wires coming off from one of the wheel sensors that's shorting to ground. Esp when it gets wet as from dew point moisture or from rain. Possibly, but somewhat doubtful.

If you just had the brakes serviced recently, and the problem started shortly there afterwords then I would definitely suspect the (a) wheel sensor.

If it's been a problem from DAY ONE, or even under the original warranty period then it needs to be fixed for FREE under that original warranty. No bones about it.

What's probably happening is that the sense wire from whichever wheel sensor is bad is shorting out and causing the ABS FAULT LIGHT to come on. I seriously doubt that you will get a CHECK ENG code fault, as this is purely a BRAKE ABS fault.

One thing you might do is pull the main wiring harness connector off of the ABS unit itself and check it for MOISTURE on the contacts. If any is found then that is your problem point.

Even if no moisture is spotted get a can of waterproofing spray from you local automotive parts store and spray out both sides of the ABS wiring harness connectors.

Since this is purely a MOISTURE related ABS Warning Light issue/problem it has to be one or the other and nothing else.

Sometimes it's best to check for this issue at night with a good bright LED type light, as then the MOISTURE will show up better then in the daytime.

If this fixes the problem please post the result.

Frank

Ok, the '03 Jeep Grand Cherokee uses a small vacuum line to control the servos. Since your light comes on, it's obviously getting power. 9 out of 10 times it's the vacuum hose.
Pop the hood and look on the passenger side towards the back for the engine coolant reservoir. It's most likely underneath it so you may have to remove the res. Check the vacuum hose and all vac. connections then check the electrical connections. If that's not the problem, check the cruise control connection to the throttle linkage.
If that still doesn't do it, you may need use scan tools and diagnostic procedures that are out of the scope of home mechanics.
Wish ya luck!

open hood and ck for broken vacuum hoses going to the purge valve(2 vacuum ports and a wiring connector)
on the drivers side between airbox and firewall
if good remove driver side rear tire and inspect hoses next to the gas tank and 3rd, the canister is in that wheel well also insp for cracked hoses there also, been working for jeep 12 years i charged people about 1 hour to correct this probem.

Trouble Code: P1491 You PCM does not sense current to radiator fan when it turns it on. Is the fan coming on or not? Usually not when you have this code. Problem can be with the fuse, relay, wiring or fan itself. First check the fuse. If good, next try swapping the relay with another one in the engine compartment relay box, such as the horn relay.
Let the car warm up and see if the fan will come on. If yes, get a new relay. If not, either use a test light to see if there is voltage at the fan connector when the engine is on and hot, or else test the fan motor by hotwiring it to the battery. If none of this works, please get back to me for how to troubleshoot the wiring.


Radiator Fan Control Relay Circuit Malfunction
Possible Causes:


Radiator fan control relay circuit is open or shorted to ground Radiator fan control relay circuit is open (test power to IGN) Radiator fan control relay is damaged or has failed PCM has failed

The codes you mention 301-302-303 are all misfire in the respective cylinders. you should replace the coil, while you are at it also verify the condition od the sparkplugs.

This will not repair the problem but it will cause your OD to shift. Caution: you need a long stretch of highway and sparse traffic.
After trying everything I could think of, I noticed that when the automatic locks failed to engage (at around 15mph) that's when the transmission would not shift into OD. So, now when the locks don't lock and the transmission doesn't shift to OD, I put the transmission in neutral and turn off the ignition and let it coast to a slow speed (see above caution). When I start the engine again and put the transmission back into drive, the locks engage and so does the OD. Works for me. I'm currently doing research on what causes the locks to engage automatically. I'm thinking it will be a vacum or a switch. BTW, mannually engaging the locks will not work. Good luck. Hope it works for you.

If your "Check Gauges" light is on, the light means pretty much whay it says...CHECK GAUGES! One or more of your gauges is/are reading outside of normal operating range. You could be having an overheating problem (Temperature gauge near or in the red) You could be having a charging system problem (Battery or Amp gauge reading in the "discharge" or "low voltage" area.) You could be nearly out of fuel (Fuel gauge reading near empty) Your oil pressure could be low (OIl Pressure gauge reading very low)....You have to look at your gauges to find out what is going on that is not normal.

P0243 - Turbocharger Wastegate Solenoid A Malfunction
Possible causes - VPWR circuit open to SCB (solenoid controlled boost) solenoid.
- SCB solenoid circuit shorted to PWR GND or CHASSIS GND.
- Damaged SCB solenoid.
- SCB solenoid circuit open.
- SCB solenoid circuit shorted to VPWR.
Possible solution Disconnect SCB solenoid. Connect test lamp to SCB solenoid harness connector. Cycle SCB driver in PCM by Output Test Mode. Test lamp cycle on and off - SCB solenoid is suspect. Test lamp always on - SCB signal short in harness or PCM. Test always off - SCB signal or VPWR open in harness or PCM (computer).

2003 jeep GC, or WJ jeep, it is..?
there are no 50a fuses in any JB,
there are just 4 in the PDC. engine bay.
so, JB is wrong, input to me.
ill assume F15 is correct, and not F3/7/12 in PDC
F15 feeds JB via a pink wire. (pk-wt)
this main F15 feed JB , F5,7,8,9 fuse in cab.

so pull fuse 5 to 9 there and the one that ends the drain
is the load that is leaking, (phantom drains)
easy, huh, just 4 fuse to pull.
Cab box, only. called JB on all jeeps.
jb fuse 5 is radio.
jb fuse 7 is HVAC zone control (heat?) skim mod. & auto head lamp sensor & BCM memory, (yes lots)
jb fuse 8 is (12 courtesy lamps , intrusion module(export) and VICS, vehicle info center(memory)
jb fuse 9, front12vdc power outlets (cig ports modern) Cell Phone arked there?

or login at alldata.com and see all that, in the wiring pages.

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It could be the crankshaft position sensor, but instead of replacing parts on guesswork have vehicle scanned with diagnostic code reader, it will be cheaper in the long run,
let me know how it goes