Vehicle: Jeep Liberty (KJ) 2002-2005 (approx)
Concern: Right (or left) side tail/brake bulb keeps burning out. Customer has had bulb replaced numerous times.
Cause: A loose reflector piece inside the tailight lens is touching the bulb. Shake the tailight to check for rattle noise.
Resolution: Replace both tailight assemblies with revised parts to correct.
Details: Design flaw
Vehicle: Engines with cast iron block, mostly happens on 3.7L such as in (KJ) Jeep Liberty and Dodge products.
Concern: Diagnosis has revealed that the CKP (crankshaft position) sensor needs to be replaced. Problem: The CKP sensor cannot be removed due to the engine block is rusty. The sensor will not come out of the hole. After considerable effort, now the sensor is broken and part of it remains in the engine block.
Cause: Exposure to road salt has rusted the engine block, causing the CKP hole to become smaller.
Resolution: Light blowtorch. Burn the remains of the CKP out of the hole. The cast iron can withstand the heat. Don't worry if the CKP magnet falls inside the engine; it will be quite happy in there. Use sandpaper or a hone to clean up the CKP hole. Lube the new CKP o-ring with engine oil proir to installation.
Details: Tech Tip: On 3.7L and 4.7L engines, replace both the CKP (crankshaft position) sensor and the CMP (camshaft position) sensor at the same time. Use MOPAR parts from the dealer. Every tech has been 'burned' on this one, just replace both and be done with it.
Vehicle: Jeep Liberty (KJ) with 3.7L 2002-2006
Concern: Cooling system will not build pressure. Upper radiator hose is always soft, even when engine is at normal operating temperature. Coolant reservoir appears to be overfilled when engine is hot.
Cause: The radiator cap has failed and is not holding pressure.
Resolution: Replace the radiator cap, located on the coolant reservoir which is mounted on the firewall.
Details: Typically there will be no coolant leak. The system pressure is built up by the air pocket above the coolant level in the reservoir.
Vehicle: All vehicles with 3.7L and 4.7L engines. (WJ) (KJ) (DR) (AN) Jeep Liberty, Grand Cherokee, etc.
Concern: Engine is overheating after cooling system repairs. Engine is overheating after the radiator was drained/refilled for maintenance.
Cause: The cooling system was not properly bled. There is an air pocket trapped, not allowing coolant to circulate.
Resolution: Allow the engine to cool. Remove the bleeder screw. Look where the upper radiator hose attaches to the engine for the bleeder screw. It requires a 10mm hex (Allen) type tool. Sometimes the screw will be very tight. You will need to use a high quality tool and possibly considerable force to remove it. Remove the radiator cap and fill the cooling system until coolant comes out of the bleeder screw hole. Reinstall the bleeder screw. You must use thread sealant to prevent a leak. Put the radiator cap on and retest.
Details: If the bleeder screw will not come out, remove the upper radiator hose at the engine just enough for coolant to come out while filling the system. This will work in a pinch.
Vehicle: (KJ) Jeep Liberty
Concern: A/C inoperative at times. Blower is OK, but sometimes A/C blows warm air. Intermittent.
Cause: Open circuit in low pressure switch -or- A/C compressor clutch is failing.
Resolution: Ensure that the A/C system has sufficient charge to allow operation. In other words, make sure the refrigerant is not empty. Disconnect the connector to the A/C low pressure switch located on the drier near the firewall. Use a jumper wire to connect the 2 pins inside the connector. If the clutch engages and the A/C blows cold, replace the low pressure switch. It is not necessary to evacuate the refrigerant to replace the switch. Otherwise, check the wiring to the A/C clutch for power with a test light. If power is present, but the A/C clutch is not engaged, carefully tap the clutch with a hammer handle and see if it engages. If it does, the clutch is faulty and should be replaced. Or simply replace the entire A/C compressor.
Details: Perform both tests with the engine running and A/C system on.
Vehicle: (KJ) Jeep Liberty
Concern: Lack of airflow from A/C vents. Blower is OK. Air is coming from the vents but seems like not enough volume.
Cause: The air inlet screen is obstructed by dust build-up.
Resolution: Operate the blower on high with the fresh air setting (NOT on recirculate). Is the air volume OK? Press the re-circulation button to turn re-circulation ON. Is the air volume less? If there is less airflow on re-circulation, remove the glove box door. Examine the screen on the air inlet for dust build-up. If present, use a hook tool to remove the screen. It is not necessary.
Details: No other models have a screen.
Vehicle: All vehicles. (JK)(ZJ)(CS)(JC)(TJ)(XJ)(PT)(KJ)(KK)(KA)(AN)(ND)(DR)(DS)(WJ)(WK)(XK)(LX)(LH)(FJ)(JR)(JS)(RT)(RS)(NS)
Concern: The MIL (check engine light) is on. The scan tool reveals DTC P0601 PCM internal controller failure.
Cause: The PCM (engine computer) has an internal fault.
Resolution: Replace the PCM to correct.
Details: This is an easy diagnosis. When P0601 is present, the solution is always to replace the PCM. There is no other possible cause. Normally the vehicle is still driveable.
Vehicle: This case was a 2005 (KJ) Jeep Liberty.
Concern: Both headlamps are inoperative. Will not turn on. High beams are OK. Low beam headlights will not illuminate.
Cause: Both headlamp bulbs are faulty.
Resolution: Replace both headlamp bulbs.
Details: The customer had the Jeep in our shop two days previous for some engine work. Surely the headlight problem must be related to the work we did, right? Something must be disconnected. No, it's called a coincidence. Both headlamp bulbs had broken filaments.
Vehicle: All Chrysler, Jeep, and Dodge vehicles. (JK)(ZJ)(CS)(JC)(TJ)(XJ)(PT)(KJ)(KK)(KA)(AN)(ND)(DR)(DS)(WJ)(WK)(XK)(LX)(LH)(FJ)(JR)(JS)(RT)(RS)(NS)
Concern: Alternator failure. The alternator (generator) is not charging. Electrical problems.
Resolution: Hold on for a minute. Alternator failures are extremely rare on Chrysler, Jeep, and Dodge. You need to rule out the battery, wiring, and PCM first before replacing the alternator.
Details: The alternator is controlled by the PCM (engine computer). Again, true alternator failure is very rare. In ten years as a dealer service dept tech, I have replaced maybe five alternators.