2001 Jeep grand cherokee laredo 4.0 6cyl inline

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Apr 062017

Jeep Grand Cherokee LaredoWindow Regulators: will front & rear interchange from same side of vehicle?

NO. We simply compare the part numbers of each window regulator and see they are different.

Left Rear 741-374  compared to the Left Front: 741-556

Right Rear 741-375 compared to the Right Front: 741-557

Clearly the part numbers are different and should not be used in place of each other.

Window Operation

The power window system includes the Driver Door Module (DDM) and Passenger Door Module (PDM), which are mounted in their respective front door, the rear door power window switches mounted on the rear doors, and the power window motors mounted to the window regulator in each door. The DDM houses four master power window switches, the power window lockout switch and the control logic for the driver side front and rear door power windows. The PDM houses the passenger side front door power window switch and the control logic for the passenger side front and rear door power windows.

When a master power window switch on the DDM is used to operate a passenger side power window, the DDM sends the window positioning messages to the PDM over the Programmable Communications Interface (PCI) data bus. The PDM responds to these messages by sending control outputs to move the passenger side power window motors. In addition, when the power window lockout switch in the DDM is actuated to disable power window operation, this is accomplished through a lockout message sent to the PDM over the PCI data bus.

Body Control Module (BCM)

The Body Control Module (BCM) also supports and controls certain features of the power window system. The BCM receives a hard wired input from the ignition switch. The programming in the BCM allows it to process the information from this input and send ignition switch status messages to the DDM and the PDM over the PCI data bus. The DDM and PDM use this information and hard wired inputs from the front door ajar switches to control the lighting of the power window switch lamps, and to control the operation of the power window after ignition-off feature.

See the owner’s manual in the vehicle glove box for more information on the features, use and operation of the power window system.

Feb 142017

1984 Jeep CJ7Turn the key on, get gauges to move, go to start and get nothing. no click no gauges. I have replaced the starter, cable, and solenoid. wondering if there might be a fuse ? or ?


My first guess would be a lack of a ground to the engine block. The ground strap is needed to deliver battery negative to the starter. You can use a multi meter to determine if you have battery negative at the case of the starter. Then check for battery  positive voltage at the “S” terminal on the starter Solenoid while someone holds the key in the “START” position. If you see both battery positive and battery negative, replace the starter. If you do not see both you will need to trace your wiring and connections.

Jan 232017

2000 Jeep Grand Cherokee LaredoI have a 2000 Jeep Grand Cherokee Laredo V6 4×4. My brake light on the left side will not work when the headlights are on. But it will work when they are off.


First thing that comes to mind would be the wrong bulb was installed. For example. a 3057 bulb is not the same as a 3157 bulb. However not to common but something that can be ruled out.

The most common issue with this model is a internally shorted tail light assembly.

tail light assembly 2000 Jeep Cherokee

If that doesn’t take care of it, you will need to get a wiring diagram and start tracing the wiring for a short or loose ground connection.

Jan 092017

1995 Jeep Grand Cherokee LaredoI have a 1995 Jeep Grand Cherokee with a 5.2L v8. About 80,000 miles. I recently had an alignment done, and now I am having trouble with my oil pressure. (Probably not related.)
When the engine is idling, the oil pressure is about 2/3 of the way up, and as I speed up, the oil pressure gauge wiggles and twitches, and sometimes drops to about half way. When I drive fast, (60mph or faster), the gauge stays around the 2/3 mark.

What concerns me most is that there is sort of a clicking noise coming from the engine. It doesn’t sound quite like a “no oil” piston slap or whatever, but still it doesn’t sound good.

I had the oil changed after it started, and I’ve checked it several times, and the oil levels are good. Also, no check engine lights or anything, and the engine temp and voltage and idle and everything seem normal.


The most common reason for odd oil pressure readings would be a failing or faulty oil pressure sending unit.

Oil Pressure Test

Check for proper oil pressure at the sending unit passage with an externally mounted mechanical oil pressure gauge (as opposed to relying on a factory installed dash-mounted gauge). A tachometer may also be needed, as some specifications may require running the engine at a specific rpm.

  1. With the engine cold, locate and remove the oil pressure sending unit.
  2. Following the manufacturer’s instructions, connect a mechanical oil pressure gauge and, if necessary, a tachometer to the engine.
  3. Start the engine and allow it to idle.
  4. Check the oil pressure reading when cold and record the number. You may need to run the engine at a specified rpm, so check the specifications.
  5. Run the engine until normal operating temperature is reached (upper radiator hose will feel warm).
  6. Check the oil pressure reading again with the engine hot and record the number. Turn the engine OFF.
  7. Compare your hot oil pressure reading to that given in the chart. If the reading is low, check the cold pressure reading against the chart. If the cold pressure is well above the specification, and the hot reading was lower than the specification, you may have the wrong viscosity oil in the engine. Change the oil, making sure to use the proper grade and quantity, then repeat the test.

Low oil pressure readings could be attributed to internal component wear, pump related problems, a low oil level, or oil viscosity that is too low. High oil pressure readings could be caused by an overfilled

Oil Pressure Sending Unit Testing

  1. To test the normally closed oil lamp circuit, disengage the locking connector and measure the resistance between the switch terminal (terminal for the wire to the warning lamp) and the metal housing. The ohmmeter should read 0 ohms.
  2. To test the sending unit, measure the resistance between the sending unit terminal and the metal housing. The ohmmeter should read an open circuit (infinite resistance).
  3. Start the engine.
  4. Once again, test each terminal against the metal housing:
    • The oil switch terminal-to-housing circuit should read an open circuit if there is oil pressure present.
    • The sending unit-to-housing circuit should read between 15–80 ohms, depending on the engine speed, oil temperature and oil viscosity.
  5. To test the oil pressure sender only, rev the engine and watch the ohms reading, which should fluctuate slightly (within the range of 15–80 ohms) as rpm increases.
  6. If the above results were not obtained, replace the sending unit/switch with a new one.

Oil Pressure Sending Unit Replacement

oil pressure sending unit

  1. Disconnect the negative battery cable from the battery.
  2. Unplug the oil pressure sending unit wiring harness connector from the sending unit.
  3. Unscrew the sending unit from the engine block.
    To install:
  4. Install and tighten the new sending unit.
  5. Plug the electrical wiring harness into the sending unit.
  6. Attach the negative battery cable.
Dec 012016

1995 Jeep Grand Cherokee LaredoAir bubbles in the transmission fluid and slippy when its cold


Air Bubbles in the Transmission Fluid

This is an indication of the transmission fluid level being low. This may be from a leak in the system or under filled at the last transmission service. The transmission fluid level needs to be checked when the engine is hot and running, the transmission is in park and the vehicle is parked on a level surface.

When the fluid level is low the transmission will indeed slip. Continued driving like this will damage the internal clutches. Repair as soon as possible to prevent any damage. If the fluid looks burnt it may already be too late and may require a rebuild. Top off the fluid level and test the operation.

Oct 312016

2007 Jeep CompassI need a diagram for serpentine belt.


Serpentine Belt Diagram – Gasoline Engine

Serpentine belt diagram 2007 Jeep Compass

The accessory drive belt (2) is a serpentine type belt that is driven by the crankshaft pulley (6).

The belt drives the A/C compressor, generator (3), power steering pump (1) and water pump (7). Belt tension is maintained by an automatic belt tensioner (8 ).

Serpentine Belt Cleaning

Clean all foreign debris from belt pulley grooves. The belt pulleys must be free of oil, grease, and coolants before installing the drive belt.

Oct 152016

2005 Jeep LibertyMy Code reader indicates the following:
P1267 Cylinder #7 high to low short side
P1265 Cylinder #5 high to low short side
P1261 Cylinder #1 high to low short side

This is on my 2005 Jeep Liberty CRD turbo diesel with only 4 cylinders. Could this be a fuel injector issue? or maybe glow plug issue? Thanks!


Cylinder High to Low Short Side

Check valve cover wire harness connections first, including under the valve cover.

Possible causes
– Faulty Fuel Injector
– Faulty Fuel Injector Interface Module
– Fuel Injector harness is open or shorted
– Fuel Injector circuit poor electrical connection

P1261 Description

A fault is detected by the fuel injector interface module in the secondary (rearward) fuel injector circuit.

Oct 012016

2008 Jeep PatriotMy remote to open my doors would not work so I used the key. The panic alarm goes off and it would not shut off I disconnected the battery for 5 mins and when reconnecting it still the panic alarm goes off. How do I turn this off.


Try This:

  1. Disconnect battery
  2. Insert ignition key and turn it to the “ON” position(not “START”)
  3. Connect battery
  4. Move ignition key from “ON to “START”


Sep 082016

2013 Jeep PatriotWill only run 40mph


Your transmission could be stuck in limp mode. This is very common. Anything from a transmission internal malfunction to a bad speed sensor can cause the computer to put the transmission in limp mode. Chances are there are trouble codes in the computer that will point you in the right direction. Your local auto parts store will do this for free for you.

Limp Mode

If there is a fault detected with the accelerator pedal position sensor, the PCM will set the engine speed at 1100 RPM.

There are four preprogrammed modes from which the GPEC1 bases initial valve timing.

  • Starting
  • Idle or Part throttle
  • Wide open throttle
  • Limp-in or Default

From each preprogrammed mode, the GPEC1 adjusts valve timing based on operating conditions.

GPEC1 has calculated optimum intake valve timing of 112 degrees after Top Dead Center and optimum exhaust valve timing of 97 degrees before Top Dead Center. The GPEC1 pulse width modulates the oil control valves to advance or retard the camshaft to their desired location. The spool valve inside the intake oil control valve is energized and moves to allow pressurized oil into the advance chambers of the intake cam phaser. At the same time, the spool valve inside the exhaust oil control valve is energized and moves to allow pressurized oil into the retard chambers of the exhaust cam phaser. Oil enters the advance chambers of the intake phaser and the retard chambers of the exhaust phaser. Oil pressure releases the lock pin from its locked position and pushes against the rotor vane. Both the rotor vanes are moved, advancing the intake camshaft and retarding the exhaust camshaft.

Aug 192016

2001 Jeep Grand CherokeeWe changed our water pump and thermostat because my  2001 Jeep Grand Cherokee Limited 4.7l v8 would run hot while sitting. Well after we got everything done, we took it down the road. It started to run hot, check gauges light came on so I turned it off and then released pressure from radiator cap. And then tried to crank but it wouldn’t start with out foot on gas. It shuts off when you take your foot off the gas and is running like crap and is shaking. I’m stumped please help thanks


Sounds like you drove it a bit too long with the engine running hot before turning it off. If it ran just fine until the check gauges light came on, you probably blew a head gasket.

The cooling system needs to be bled and then topped off. If the top and bottom radiator hose are getting hot, then the thermostat is opening. Most common reason for overheating at idle only would be the fan is not coming on. This can be from the cooling fan relay, the fuse,  the cooling fan motor, PCM or the wiring harness.

2001 Jeep Grand Cherokee Cooling Fan Wiring Diagram