Oct 182017

Buick Century

The wiring harness was cut in a wreck. I have connected all but three solid black and three solid grey wires. They are identical. Which do I connect to which? Or does it matter? They say they go to the throttle sensor and neutral switch. Please help!!

PCM Wiring Harness Issue

You will need to identify which wire is connected to each terminal coming from the PCM. You can do this with a multi-meter by checking the continuity from the pin connector at the PCM. Then using a wiring diagram correlate the PCM connector pin with each wire and this will let you know where the wire is supposed to go.

PCM Wiring Diagram (best viewed in Chrome or Firefox)

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 182017

Ford Ranger

Diagnosed a bad throttle position sensor. Installed a new one. Ran great for about a minute. Went back to running rough. Installed another new tps. Again it ran good for about a minute. Then it ran rough again. With the voltmeter I confirmed I had good 12 volt power going in. On the third wire I confirmed a good ground loop. But on the signal wire it should read 0.9 volts on closed throttle and 5.0 volts on wide open throttle. It gave 0.3 volts closed throttle to wide open throttle. Could my signal wire be grounded somewhere? Or could my computer be fried?

Throttle Position Sensor

tps connector diagram 2003 Ford Ranger

Testing for short or open in wiring harness

Check TP Circuit for open in harness
  • Turn ignition switch to off position. Leave TP sensor disconnected. Disconnect PCM connector(s). Inspect connector for loose, damaged or corroded terminals, and repair as needed.
  • Using a digital multi-meter, measure resistance of TP circuit between PCM harness connector and TP sensor connector.
  • If resistance is less than 5 ohms go to next step below. If resistance is 5 ohms or more, repair open in TP circuit.
Check TP Circuit for short to SIG RTN or PWR GND in harness
  • Ensure PCM is disconnected. Disconnect scan tool from Data Link Connector.
  • Using a Digital multi-meter, measure resistance between TP circuit, and SIG RTN and PWR GND circuits at PCM harness connector. If either resistance measurement is 10k/ohms or less, repair short between circuits.
  • If both resistance measurements are more than 10k/ohms, replace the PCM.



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.

Oct 162017

Pontiac Grand Am

Description of Problem: I have a 2000 Pontiac Grand Am and just replaced the ignition switch. I did the passkey lock and everything with no problem. But the ignition only will start to the side not mounted in the dash where its supposed to be and I cant put my radio back in.

Not sure what you did or didn’t do. Best advice would be to go back over your work. You may want to take it all back apart and start from scratch to make sure no steps were missed. Check you connections.

Ignition and Start Switch Replacement Pontiac

(best viewed in Google Chrome or Firefox)

You must perform the BCM theft deterrent relearn procedure after replacement of the ignition switch lock cylinder.

Oct 162017

2007 Pontiac G5

How can I tell if my G5 has the VIC (Vehicle Information Center) or not. It has to do with programming a remote access AC Delco fob.

Pontiac refers to the information center as a Drivers Information Center (DIC) which is essentially the same thing. So as far as programming the new fob the answer would be yes it does.

Driver Information Center (DIC)

Your vehicle has a Driver Information Center (DIC). The DIC display gives you the status of many of your vehicle’s systems. The DIC is also used to display driver personalization menu modes and warning/status messages. All messages will appear in the DIC display, located at the bottom of the instrument panel cluster.

drivers information center button

The DIC buttons are located on the left side of the steering wheel.
(Information): Press this button to scroll through the vehicle information mode displays.

(Reset): Press this button to reset some vehicle information mode displays, select a personalization menu mode setting, or acknowledge a warning message.
Press and hold the information and reset buttons at the same time for one second, then release the buttons to enter the personalization menu.

Driver Information Center (DIC) Description and Operation

The driver information center (DIC) displays important vehicle information when it first powers up. The DIC is also used to display Odometer and Outside Air Temperature when other important vehicle information is not being displayed. The DIC switches are hardwired to and read by the instrument panel cluster (IPC). The IPC provides power to the DIC switches via the IPC ignition 1 voltage circuit fused in the body control module (BCM). The BCM is responsible for driving and processing the DIC display through GMLAN serial data. The BCM is responsible for reading the outside air temperature (OAT) and season odometer. The outside air temperature and season odometer is transmitted to the IPC over GMLAN for display in the DIC. The OAT data is transmitted in degrees Celsius and the cluster is responsible for converting the outside air temperature (OAT) to Fahrenheit.

There are 2 DIC buttons on the instrument panel cluster (IPC):

  • INFO

The 2 DIC buttons however provide 3 switch functions. Pressing the INFO and SET/RESET button at the same time provides the MENU switch function.

The INFO button is used in order to navigate through the following driver information center (DIC) information modes:


Other instrument panel cluster (IPC) information displayed in the DIC are Season odometer and Outside Air Temp.

2009 Honda Jazz – Brake Shudder

 Auto Repair Questions, Honda  Comments Off on 2009 Honda Jazz – Brake Shudder
Oct 152017

Honda Jazz

Hi All. Our Honda Jazz has developed a ‘shudder’ when braking. It only happens when the brakes are applied and it is noticeable past 40km/h. As an example: If I am driving down the highway and apply the brakes (even with light to medium pressure), the front of the car shudders/shakes. There are no abnormalities in the tyres so I’m thinking the discs are warped? Is there any other reason for this shudder? The car has done approximately 167,000kms and runs like a dream. Any help would be greatly appreciated. Cheers.

Brake Shudder

In my experience 99.9% of the time this is caused from warped rotors. The other 0.01% is caused from tire wear. The important thing here is to determine why the rotors are warped. Was there a panic stop where you had to slam on the brakes at a high rate of speed? Is one of the calipers sticking causes the brake pads to continuously rub on the rotors causing them to get excessively hot? Are the brake pads just worn out?

In any case it is best to replace the brake pads at the same time as the rotors. This will give the brake pads and rotors new clean surfaces to work with. Otherwise you may end up with some unwanted brake noise.

2004 Chevrolet Trailblazer ABS

 Auto Repair Questions, Chevy  Comments Off on 2004 Chevrolet Trailblazer ABS
Oct 112017

Chevy Trailblazer

My wife’s car has had an abs light on since right after we bought it. I had the codes read. They said it was the wheel speed sensor. I changed out both wheels speed sensors and put brand new brake pads on the front and back as well as new calipers all the way around. She said she drove it today the light still on and it was raining. She was coming to a stop sign and hit the brakes. It made an awful noise and it didn’t want to come to a stop. I have replaced the master cylinder and I have bled the brakes. I have also sanded down all the ground leads and put them back on and sprayed with undercoating as stated. Someone told me it could be the EBCM what should I do or change?

The description of what your wife told you would indicate the ABS was functioning properly. When the roads are wet or icy the ABS motor will activate, making a groaning noise, this prevents the wheels from locking up. When the ABS is activated the light may illuminate temporally and generally goes back off. If the light is on continuously the ABS will not function.

If you want to make sure the ABS doesn’t come and go you can disable the function by removing the ABS fuse or relay. Doing so will allow the brakes to function like all the old cars used to without ABS. Learning to brake a little earlier will help slow the car and also cause your brake pads and rotors to last longer. You can drive the car this way as long as you like but the ABS light will remain on.

If you want to repair the ABS system the use of a scan tool will be required for individual testing of components.

Antilock Brake System (ABS) Warning light

With the Anti-Lock Brake System (ABS), this light will come on when you start your engine and may stay on for several seconds, that is normal.

A chime may also sound when the light comes on.

If the light stays on, or comes on when you are driving, your vehicle needs service. When the regular brake system warning light is not on, you still have brakes, but you do not have anti-lock brakes. If the regular brake system warning light is also on, you do not have anti-lock brakes and there is a problem with your regular brakes. See Brake System Warning Light earlier in this section.

The ABS warning light should come on briefly when you turn the ignition key to RUN. If the light does not come on then, have it fixed so it will be ready to warn you if there is a problem.

Antilock Brake System

When wheel slip is detected during a brake application, the ABS enters antilock mode. During antilock braking, hydraulic pressure in the individual wheel circuits is controlled to prevent any wheel from slipping. A separate hydraulic line and specific solenoid valves are provided for each wheel. The ABS can decrease, hold, or increase hydraulic pressure to each wheel brake. The ABS cannot, however, increase hydraulic pressure above the amount which is transmitted by the master cylinder during braking.

During antilock braking, a series of rapid pulsations is felt in the brake pedal. These pulsations are caused by the rapid changes in position of the individual solenoid valves as the EBCM responds to wheel speed sensor inputs and attempts to prevent wheel slip. These pedal pulsations are present only during antilock braking and stop when normal braking is resumed or when the vehicle comes to a stop. A ticking or popping noise may also be heard as the solenoid valves cycle rapidly. During antilock braking on dry pavement, intermittent chirping noises may be heard as the tires approach slipping. These noises and pedal pulsations are considered normal during antilock operation.

Vehicles equipped with ABS may be stopped by applying normal force to the brake pedal. Brake pedal operation during normal braking is no different than that of previous non-ABS systems. Maintaining a constant force on the brake pedal provides the shortest stopping distance while maintaining vehicle stability.

Programming the Traction Control Automatic Engagement Feature

The automatic engagement feature may be programmed so that the traction control system activates or does not activate automatically at the start of each ignition cycle. In order to change the status of the automatic engagement feature, perform the following procedure:

Important Failure to follow the correct procedure may cause DTC C0283 to set in EBCM memory.

  • Park the vehicle and apply the parking brake.
  • Unlock the ignition and shift the transmission into NEUTRAL (N).
  • Turn the ignition ON, engine OFF.
  • Press and hold the brake pedal and the accelerator pedal.
  • Press and hold the traction assist switch for 5 seconds.
  • Release the brake and accelerator pedals and the traction control switch.
  • Turn the ignition OFF.
Oct 112017

2004 Buick Rainer

I can’t get the A/C or Heat to come out the front vents. The vents are open, it will work on windshield, floor, and back vents. I have checked the fuses and none are blown. What do u advise? If not to complicated I would like to do it myself. Also what part would I need and what would that be called?
Thank You,

This sounds to me like a failed mode door actuator. Its failure is so common that Dorman has come up with a better direct replacement version.
Part you will need: Dorman 604-110 Air Door Mode Actuator

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Mode Actuator Replacement

Removal Procedure

  • Remove the left side sound insulator screws.
  • Remove the left hand floor duct.

Mode Actuator 2004 Buick Rainer

  • Disconnect the electrical connector from the mode door actuator.
  • Remove the screws from the mode actuator (1).
  • Remove the mode door actuator.

Installation Procedure

Important The new actuator is in Bi-Level mode. Place the door in the middle of the travel position before you install the actuator.

  • Install the mode actuator (1).
  • Install the screws to the mode door actuator (1).

Tighten the screws to 1.9 N·m (18 lb in).

  • Install the left hand floor duct.
  • Install the left side sound insulator screws.
  • Recalibrate the mode actuator.