Oct 022018

2004 Jeep Grand Cherokee

Windows, Locks, 1 Mirror problem. Front Driver door controls, lock switch only locks/unlocks front driver’s door. Window switches only open/close driver’s side front & rear windows. Front Passenger door switches do NOT lock/unlock doors or open/close windows. Rear driver’s door window switch works. Rear Passenger door window switch does NOT open/close the window. Keyless entry remotes do NOT work (Batteries are good) Interior lights come on with all door except the front passenger side. Driver’s mirror does adjust, Passenger mirror does NOT adjust. All wires running into the front doors have passed a continuity test. I’m leaning towards the Front Passenger side door module. What do you think?

I have found over the years that the wiring harness in the door jam becomes damaged easily. This is more common than you might think on older vehicles. Not the rule but worth checking. It is quite possible that the door module may be faulty or both.

Jun 182018

Jeep Commander

No start after radio replacement

My son replaced his radio yesterday and now the jeep will not crank. He has tested the battery, alternator, and starter. He has also checked the spark plugs. He replaced the ignition switch and the jeep seems like its trying to crank but it is not turning over. He is thinking this may be related to something electrical.

He, your son, is most likely correct in thinking it is something electrical. It worked just fine before it was worked on. So most likely a fuse was blown or a wire shorted during the installation of said radio. Checking all the fuses is a safe place to start. Then move on to double checking all the work done during the radio replacement.

Engine Swap 2002 Jeep Liberty

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Jun 182018

2003 Jeep Liberty

I have a 2003 liberty engine. I was wondering if there will be any setbacks, problems, or augmentations I will have to make to have it fit into my 2002 liberty.

As long as the engine size is the same(2.5L, etc) there should be no issues whatsoever.

Dec 192017

Jeep Grand Cherokee Laredo

I replaced my brake booster. Now my lock on the driver side won’t lock all the doors like it should. My keyfob stopped working and my dome lights stay on. Is this a coincidence or did I maybe bump something?

Dome light stays on

Coincidence. The door ajar switch and door lock assembly are connected. The dome light is staying on because it thinks the door is still open(ajar). This may also be why the keythob doesn’t feel like working.

Dec 082017

Jeep Grand Cherokee Laredo

Mechanical Wining Noise

I’m not very car savvy. My car had made some sounds that sounded like a rusty shock almost, especially when turning. Then today after pulling it into a parking spot and turning it off, it continued to make sound. The sound was like a mechanical wining (fairly loud considering the engine being off) and it slowly dropped in pitch until stopping.

Burning Smell

Towards the end of the decline in pitch a white smoke began to come out of the hood, and a burning smell (not that dissimilar to the smell of rubber became very strong and still exists within the car. The car’s battery seems to be absolutely fine but the car doesn’t respond at all when I try to start it. The oil gauge is also a little low, but I THINK I know how to check the oil and I THINK it was at a decent volume.

I have no idea, and would just love any input as to what the hell just happened. THANK YOU!

Tough to diagnose a noise without hearing it but I’ll do my best.

My first thought is a pulley locked up and caused the serpentine belt to break. I would look to see if the belt is missing or burnt in a particular spot. Possibly the bearings went out of a idler pulley or tensioner pulley.(bearing failure is quite whinny)  Or the alternator locked up. All of which are rotated with the serpentine belt. If a pulley locked up it would cause the belt to burn (emit smoke as well) as it is being pulled over it. The belt also rotates the alternator which charges the battery. So if this was the issue the alternator wouldn’t be able to perform properly and would leave you with a weak battery.

The lights and radio may come on but the engine does nothing when you try to start it. This is normal for a weak battery. The radio requires as little as 5 amps to operate, the headlights up to 30 amps and the starter requires 250 amps. Big difference there.

You’ll probably need to have the battery fully charged(or replaced if older than 4 years) and the belt replaced. This is along with whatever part failed whether its a pulley, tensioner or alternator.

Nov 072017

Jeep Grand Cherokee

Jeep will only start on second crank. Driving for 10 minutes and seems like it loses power, rpm drop , catch again, when I get it going it hobbles along and will not exceed 20mph or above 1500 rpm. Had vacuum serviced but problem came back??.

My first thought is fuel pressure regulator. The regulator acts as a check valve to maintain some fuel pressure when the engine is not operating. This will help to start the engine. A second check valve is located at the outlet end of the electric fuel pump. This is assuming the check engine light is not on.

Fuel Pressure Regulator/Fuel Filter

A combination fuel filter and fuel pressure regulator is used on all engines. It is located on the top of fuel pump module.

fuel pressure regulator location diagram 1998 Jeep Grand Cherokee

Fuel Pressure Regulator Operation:

The pressure regulator is a mechanical device that is not controlled by engine vacuum or the Powertrain Control Module (PCM)

The regulator is calibrated to maintain fuel system operating pressure of approximately 339 kPa ± 34 kPa (49.2 psi ± 5 psi) at the fuel injectors. It contains a diaphragm, calibrated springs and a fuel return valve. The internal fuel filter is also part of the assembly.

Fuel is supplied to the filter/regulator by the electric fuel pump through an opening tube at the bottom of filter/regulator.

fuel pressure regulator 1998 Jeep Grand Cherokee


Oct 182017

Jeep Grand Cherokee

Lately my vehicle wants to stall and having a hard time staying in gear. I checked the trans fluid and there was no reading on the stick . I haven’t driven it since I filled it and I don’t notice any leaks.

Fluid Loss

Some leaks only happen under pressure. You may need to bring the engine to operating temperature and drive it. Then park it over a clean piece of card board and leave it set over night. This should determine if there is an external leak.

Another option may be an internal leak. Sometimes when the radiator busts internally the transmission fluid leaks into the cooling system. You may notice a discoloration of the engines coolant.

Oct 162017

Jeep Cherokee

Recently it started stalling out in traffic, but would start right back up no problem. Then stalls back out a few more miles down the road but again start right back up. The sensors check out fine, coil checks out fine, replaced the cam sensor that the on board computer says was bad. It is still stalling out but only in drive never at an idle. The only thing I can find wrong is only getting 9.4 volts to sensors the cam and the crank.

Generally when the computer sets a code for the cam position sensor it goes into default mode. This means it uses preset parameters to allow the engine to continue to run. The most common reason for the issue you have described would be a failing ignition control module. However the functions of the ignition control module are performed by the Electronic Control Unit (ECU), also known as the Powertrain Control Module. You stated that you already tried replacing it. My first thoughts would be if it was a reman unit from Autozone, you might want to take it back and try another one.

Next thought since you stated a lower than normal voltage reading that there might be an issue with the wiring harness. Maybe looking the harness over for any breaks or rubbing. Or even going more in-depth and performing a continuity test on each wire.

Camshaft Position Sensor Operation – 1993 Jeep Cherokee 4.0L

The Camshaft Position Sensor, or CMP sensor is located inside the distributor. The PCM uses the CMP signal to determine the position of the No. 1 cylinder piston during its power stroke. The PCM uses this information in conjunction with the crankshaft position sensor to determine spark timing among other things.

The CMP sensor contains a Hall effect device which sends either a 0.0 volt or a 5.0 volt signal to the PCM depending on the position of the distributor shaft.

If the cam signal is lost while the engine is running, the PCM will calculate spark timing based on the last CMP signal and the engine will continue to run. However, the engine will not run after it is shut off.

camshaft position sensor location diagram Jeep Cherokee

Hall-effect CMP Testing

1.Connect a scan tool to the data link connector (DLC) and check the CMP sensor datastream for a normal waveform.
2.If the scan tool waveform for the CMP sensor is not within the specified values perform a visual inspection on the CMP sensor, wiring harness, connector and related components as follows: ◦Ensure that the connector tabs are fully locked
◦Check for corroded terminals
◦Bent pins
◦Pins pulled back in the connector
◦Terminal cavities spread open
◦Harness damage
◦Sensor damage

3.If the connectors, wiring harness and related mechanical components pass inspection, perform the following procedures to test the CMP sensor, wiring and related modules: A.Disconnect the CMP sensor connector.
B.Check the CMP power input circuit by performing a circuit resistance test between the CMP sensor and the power input. Use the Component Pin Data for circuit details.
C.Check the MAF sensor signal circuit to the PCM by performing a circuit resistance test between the MAF sensor and the PCM. Use the Component Pin Data for circuit details.
D.Check the MAF sensor ground circuit between the MAF sensor and PCM by performing a circuit resistance test. Use the Component Pin Data for circuit details.
E.Repair/replace defective parts as needed and recheck the scan data.