Jul 262016

transmission filter changeWhat are the signs of a dirty transmission filter. When  is it time for a transmission filter change?


Shouldn’t be any signs, most transmission filters are changed by age instead of fluid color.

It is recommended that the transmission filter and fluid be changed every 12,000 miles according to the manufacturer. for 3/4 ton trucks and larger. Every 15,000 miles for 1/2 ton trucks.

Use Dexron lll(r) or its superseding fluid type.

Check the level of the fluid at least once a month. The fluid level should be checked with the engine at normal operating temperature and running. If the truck has been running at high speed for a long period, in city traffic on a hot day, or pulling a trailer, let it cool down for about thirty minutes before checking the level.

  1. Park the truck on a level surface with the engine idling. Shift the transmission into  P and set the parking brake.
  2. Remove the dipstick (on newer models, you may have to flip up the handle first), wipe it clean and reinsert if firmly. Be sure that it has been pushed all the way in.
  3. Remove the dipstick and check the fluid level while holding it horizontally. All models have a HOT and a COLD side to the dipstick.

Transmission Filter Change and Fluid 1988 GMC 1500

  • The fluid should be drained with the transmission warm. It is easier to change the fluid if the truck is raised somewhat from the ground, but this is not always easy without a lift. The transmission must be level for it to drain properly.
  • Place a shallow pan underneath to catch the transmission fluid (about 5 pints). Loosen all the pan bolts, then pull one corner down to drain most of the fluid. If it sticks, VERY CAREFULLY pry the pan loose. You can buy aftermarket drain plug kits that makes this operation a bit less messy, once installed.NOTE: If the fluid removed smells burnt, serious transmission troubles, probably due to overheating, should be suspected.
  • Remove the pan bolts and empty out the pan. On some models, there may not be much room to get at the screws at the front of the pan.
  • Clean the pan with solvent and allow it to air dry. If you use a rag to wipe it out, you risk leaving bits of lint and threads in the transmission.
  • Remove the filter or strainer retaining bolts. On the Turbo Hydra-Matic 400, there are two screws securing the filter or screen to the valve body. A reusable strainer may be found on some models. The strainer may be cleaned in solvent and air dried thoroughly. The filter and gasket must be replaced.


Jul 222016

1995 GMC JimmyWhere is the timing sensor at and I’m getting gas in the oil?


The timing sensor is known as the Crankshaft Position Sensor. (See Engine Sensors). The Crankshaft position sensor location is behind the harmonic balancer in the timing chain cover at the bottom. As for gas in the oil, look for a foiled spark plug or a sticking fuel injector that may be leaking.

crankshaft position sensor location 1995 GMC Jimmy

Crankshaft Position Sensor Location and Replacement 1995 GMC Jimmy

Removal Procedure

  • Remove the electrical connector.
  • Remove the sensor hold down bolt.
  • Remove the sensor from the timing cover.


 When installing or removing a crankshaft position sensor (CKP) make sure the sensor is fully seated and held stationary in the front cover before torquing the hold down bolt into the front cover. A sensor which is not seated may result in erratic operation and lead to the setting of false codes.
  • Inspect the sensor 0-ring for wear, cracks or leakage.

Replace if necessary. Lube the new o-ring with clean engine oil before installing.

Installation Procedure


 Make certain that the Crankshaft Position (CKP) sensor mounting surfaces are clean and free of burrs before installing the CKP sensor.
  • Install the sensor into the timing cover.
  • Install the sensor hold down bolt.


Tighten the hold down bolt to 8 N·m (71 lb in).

Caution! Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  • Install the electrical connector.


Jul 072016

2001 GMC SonomaHave gurgling noise when I shut off engine. Temp gauge shows no sign of overheating. No steam or leaking! Plz help?


This can happen when the coolant mixture is mostly water. First thing to do would be to check the radiator coolant level and the overflow level. If it is low, look for a leak and repair. Then retest and see if it still has the gurgling noise.

Follow the image for more Details…
If the coolant level is full, there is a possibility that some of the engine compression is getting into the system. You can connect a coolant system pressure tester and start the engine. You will notice an increase in pressure well over the normal 17 – 21 lbs.

Jun 032016

1991 Chevy s10Transmission completely went out. Bought a transmission from wrecking yard, worked great for 10 miles. In the morning the speed cable was leaking transmission fluid really bad. Stopped shifting out of first. Filled fluid and it still wont shift up from first and started shifting hard. If I repair leak will it start shifting?


No. Buying a used transmission is a gamble. It is like getting your hands on the original transmission just 10 miles before it went out on you. And they usually do not carry any type of warranty.

I recommend a re-manufactured engines and transmissions that comes with a parts and labor warranty.

Jun 032016

2008 GMC SierraInterior lights will not come on when opening the door on driver’s side. The other doors work properly. What is wrong with the interior lighting?


Most likely reason would be the driver’s door latch assembly is faulty and or the wiring harness or connection at the door latch.

Courtesy/Illuminated Entry Lamps

 The courtesy/illuminated entry lamps, may be manually turned ON or OFF by placing the interior lamp switch in the ON or OFF position. If an outside door handle is lifted and a door is opened, the courtesy/illuminated entry lamps illuminate. After all the doors have been closed the courtesy/illuminated entry lamps will remain illuminated approximately 15 seconds. The body control module (BCM) will then turn them OFF through the theater dimming feature. The courtesy/illuminated entry lamps will also turn ON prior to any door being opened, and remain illuminated approximately 40 seconds when the driver removes the ignition key. When the driver places the dome lamp defeat switch in the OFF position, the courtesy/illuminated entry lamps will be disabled.

The BCM and the door modules communicate through the GMLAN serial data circuit for the lamp illumination commands of the door switch signals. The left and right rear door latch switches are both on one circuit that is also an input to the BCM.

The left and right front door courtesy lamps (if equipped) receive voltage and ground from the driver door switch and the passenger door switch respectively. The remaining courtesy lamps are controlled and receive voltage from the BCM. Voltage for the courtesy lamp supply voltage circuit is from the INT LTS fuse in the instrument panel fuse block.

2008 GMC Sierra interior lighting wiring diagram

May 042016

1996 GMC 1500my truck wont start when its cold but everything electrical comes on… what is wrong?


Most likely reason would be the battery is weak or bad connections at the battery including corrosion. The next time it will not start check for battery positive at the “S” terminal on the starter while someone holds the ignition key in “START”. If you see battery voltage and have a good ground, replace the starter. If not trace back to see where you lost battery positive.

Use the wiring diagram provided to help narrow down the issue.



Apr 262016

2010 GMC TerrainPaddle shifter won’t work on my 2010 GMC Terrain slt 6cyl.. Whats the cause and repair?



The paddle shifter utilizes the up and down switches that sends signals to the body control module(BCM). Could be any part of the circuit. The switches, the BCM, the wiring harness or as simple as a fuse. Each will need to be checked to determine the exact cause before the repair can be made. Of course it would be great if it was just a blown fuse causing all the issues so be sure to check that first.

Paddle Shifter Wiring Diagram

Use the wiring diagram provided to trace the wiring harness and gain a better understanding of how the switches signal the transmission through the BCM.

paddle shifter wiring diagram

Feb 172016

2000 GMC Sierra
The code reader says camshaft position sensor low voltage. I’ve had issues the last few months with it being hard to start and stalling on occasion I put my code reader on it. I have replaced both crank and cam sensors. Problem still exists. Ive checked what I could as per why the camshaft sensor low voltage comes up and now I’m stumped.



Code P0342 – Camshaft Position Sensor Circuit Low Voltage

Camshaft sensor low voltage possible causes

  • Faulty Camshaft Position Sensor
  • Camshaft Position Sensor harness is open or shorted
  • Camshaft Position Sensor circuit poor electrical connection
  • Faulty starter motor
  • Starting system circuit
  • Dead (Weak) battery

Camshaft sensor low voltage possible symptoms

Camshaft sensor low voltage related symptoms

The following symptoms can be caused by intermittent wiring connections or faulty signal to the EMS:

  • Extended crank time with a cold engine
  • Intermittent rough running
  • Unstable idle
  • Bucking
  • Hesitation
  • Stumble
  • Chuggle
  • Poor fuel economy
  • Stalling on acceleration

Camshaft sensor low voltage operation

Engine Management Systems (EMS) use the camshaft position sensor to manage sequential fuel injection and as part of misfire diagnosis. The EMS constantly monitors the number of pulses on the signal circuit. The EMS compares the number of camshaft sensor reference pulses and the number of crankshaft position sensor reference pulses received. If the EMS receives an incorrect number of pulses, Diagnostic Trouble Codes (DTCs) should be stored in the EMS. Some engine management systems will then default to multi-port or “gang-fire” injector operation. The camshaft position sensor signal is required to sequence the injector operation to the proper cylinder timing. If the camshaft position sensor or circuit is faulty most engines will start. The EMS misfire diagnostic will likely be affected.

camshaft sensor low voltage

– Camshaft Position Sensor CMP

Dec 222015

1995-gmc-jimmy-2 3 shops have looked at it. I replace the spider injectors, fuel pump, fuel filter, fuel pressure regulator, spark plugs, wires, distributor rotor, MAP sensor, throttle position sensor. Ideals great push gas it acts like it starved for gas. 3Rd shop wants to put a more expensive fuel pump on it. Do you think this will help?

Dec 182015

My USB port does not work on the truck. When I took the radio out of the truck, there is a mini USB male hanging out of the harness, but no plug in for the USB on the back of the radio. Is this not the radio/navy that came in it? Whoever owned it before me spliced into all sorts of wires and obviously had an aftermarket system. What should I do to get the USB working. Is there a wiring harness with the USB on it or am I just up the creek?