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Jim Taddei

Jim Taddei has been in the automotive field since 1975 and has over 25 years of experience with General Motors products, achieving the designation of GM Master Technician. He is also currently certified as an ASE Master Technician, and holds an Advanced California Smog Check License. He has been the lead technician and team leader at a multi-line dealership. After leaving the dealership he spent a couple of years working in an independent shop and now uses his experience and expertise to help verify the quality of RepairPal Certified shops.

Posts by Jim Taddei

Anti-Lock Brake System: Why It's Important and How It Works

The purpose of an anti-lock brake system (ABS) is to prevent the wheels from locking up or skidding during braking. If the brakes lock up, the vehicle takes longer to stop and the ability to steer the vehicle is greatly diminished.

The purpose of an anti-lock brake system (ABS) is to prevent the wheels from locking up or skidding during braking. If the brakes lock up, the vehicle takes longer to stop and the ability to steer the vehicle is greatly diminished.

GM Passlock Security Light Issues

In this article we will be looking at various factory-installed General Motors anti-theft systems. Outlined below are some of the common problems and solutions to those problems.

In this article we will be looking at various factory-installed General Motors anti-theft systems. Outlined below are some of the common problems and solutions to those problems.

GM VATS (Vehicle Anti-Theft System)

VATS (Vehicle Anti-Theft System) is the original GM starter interrupt anti-theft system. Characterized by the resistor found in the blade of the ignition key, VATS was used on many GM makes and models from the mid 1980s through the early 2000s.

VATS (Vehicle Anti-Theft System) is the original GM starter interrupt anti-theft system. Characterized by the resistor found in the blade of the ignition key, VATS was used on many GM makes and models from the mid 1980s through the early 2000s.

GM Passlock Anti-Theft Systems

The Passlock I system is considered the replacement for the GM Vehicle Anti-Theft System (VATS). The Passlock II and III (PK3) systems followed shortly after the introduction of the Passlock I system.

The Passlock I system is considered the replacement for the GM Vehicle Anti-Theft System (VATS). The Passlock II and III (PK3) systems followed shortly after the introduction of the Passlock I system.

GM 4WD Warning Light Issues

Is your 4WD light flashing? Will your 4WD not engage? Is your 4WD warning light on or a "Service 4WD System" message displayed? Please read the article below for information, common problems, and possible solutions to these issues.

Is your 4WD light flashing? Will your 4WD not engage? Is your 4WD warning light on or a "Service 4WD System" message displayed? Please read the article below for information, common problems, and possible solutions to these issues.

Transfer Case Control Module

The Transfer Case Control Module (TCCM) is the brain behind the electronically shifted GM 4WD systems.

The Transfer Case Control Module (TCCM) is the brain behind the electronically shifted GM 4WD systems.

Transfer Case Encoder Motor

The encoder motor is an electric motor which is used to shift the transfer case from high to low range. Also included in the encoder motor assembly is a position sensor which sends the actual position of the transfer case shift shaft to the transfer case control module.

The encoder motor is an electric motor which is used to shift the transfer case from high to low range. Also included in the encoder motor assembly is a position sensor which sends the actual position of the transfer case shift shaft to the transfer case control module.

Front Differential Actuator

The front differential actuator is an electric or cable operated actuator that engages the central disconnect feature in the carrier of the front differential, resulting in 4WD operation.

The front differential actuator is an electric or cable operated actuator that engages the central disconnect feature in the carrier of the front differential, resulting in 4WD operation.

GM Theftlock Radio Issues

Do you see "LOC" or "INOP" displayed on your GM radio? If so, please see the article below for important information about the GM Theftlock Radio System. To unlock the Theftlock system when the user code is unknown, perform the following steps: Press and hold buttons 2 and 3 until a three digit code appears on the display.

Do you see "LOC" or "INOP" displayed on your GM radio? If so, please see the article below for important information about the GM Theftlock Radio System. To unlock the Theftlock system when the user code is unknown, perform the following steps: Press and hold buttons 2 and 3 until a three digit code appears on the display.

Toyota Accelerator Pedal & Floor Mat Recalls

Important, if you feel your vehicle has this unintended acceleration issue: If you have noticed any of the following: Your accelerator pedal is harder than normal to depress, not smooth during operation, or slow to return after being depressed the vehicle should be stopped at the nearest safe location, the engine shut off, and a Toyota dealer contacted for assistance. .

Important, if you feel your vehicle has this unintended acceleration issue: If you have noticed any of the following: Your accelerator pedal is harder than normal to depress, not smooth during operation, or slow to return after being depressed the vehicle should be stopped at the nearest safe location, the engine shut off, and a Toyota dealer contacted for assistance. .

GM OBD I Trouble Code Chart

Code Description Code 12 No distributor reference pulse (diagnostic test active) Code 13 Oxygen sensor circuit open or no activity Code 14 Engine coolant temp sensor error (high temp indicated) Code 15 Engine coolant temp sensor error (low temp indicated) Code 16 System voltage too low Code 17 Camshaft position sensor error Code 21 Throttle position sensor error (signal high) Code 22 Throttle position sensor error (signal low) Code 23 Intake air temp sensor error (low temp indicated) Code 24 Vehicle speed sensor error (open circuit or no activity) Code 25 Intake air temp sensor error (high temp indicated) Code 26 Quad Driver Module (QDM A) error Code 28 Auto transmission range pressure switch error Code 31 Wastegate solenoid circuit error Code 31 Gear Position Switch (PRNDL) error Code 32 Baro sensor circuit error / EGR circuit Error / MAP sensor signal open Code 33 MAP sensor circuit error (signal high indicating low vacuum) Code 34 MAP sensor circuit error (signal low indicating high vacuum) Code 35 IAC problem or idle error Code 36 MAF sensor error / 24x crankshaft position sensor circuit error / 4T60-E Shifting error Code 37 TCC brake switch circuit error Code 38 TCC brake switch circuit error Code 39 Clutch switch circuit error / Torque converter clutch error Code 41 Ignition control error / MEM-CAL error / C³I Cam Sensor Signal error Code 42 Ignition bypass circuit error Code 43 Knock sensor error Code 44 Oxygen sensor error (lean condition indicated) Code 45 Oxygen sensor error (rich condition indicated) Code 46 Pass-Key II (VATS) system error - circuit out of freq range Code 47 UART (serial data) circuit error Code 51 PROM error / Incorrect MEM-CAL Code 52 Fuel cal-pak incorrect or missing Code 53 System voltage too high Code 53 Digital EGR valve solenoid 1 error Code 54 Fuel pump circuit low voltage / Digital EGR valve solenoid 2 error Code 55 ECM error / Digital EGR valve solenoid 3 error Code 56 Quad Driver Module (QDM B) error Code 57 Boost control error Code 58 Trans fluid temp sensor circuit error (low voltage) / VATS system error Code 59 Trans fluid temp sensor circuit error (high voltage) Code 61 A/C system performance Code 63 Right bank O2 sensor circuit error / MAP sensor circuit signal voltage high (low vacuum indicated) Code 64 Right bank O2 sensor lean exhaust indicated / MAP sensor circuit signal voltage low (high vacuum indicated) Code 65 Right bank O2 sensor rich exhaust indicated Code 66 A/C pressure sensor circuit error (low pressure indicated) Code 67 A/C pressure sensor circuit error Code 68 A/C clutch relay circuit error (shorted to ground) Code 69 A/C clutch relay circuit error (open circuit indicated) / A/C high pressure switch error Code 70 A/C pressure sensor circuit error (high pressure indicated) Code 71 A/C evaporator temp sensor circuit error (low temp indicated) Code 72 VSS signal circuit error Code 73 A/C evaporator temp sensor circuit error (high temp indicated) Code 75 Digital EGR solenoid #1 circuit error Code 76 Digital EGR solenoid #2 circuit error Code 77 Digital EGR solenoid #3 circuit error Code 79 Transmission fluid over temp Code 80 Transmission component slipping Code 82 3x crankshaft position sensor circuit error Code 85 PROM error Code 86 ECM Analog/Digital error Code 87 EEPROM error (flash memory error) Code 90 TCC error Code 93 Transmission pressure control solenoid circuit error Code 96 Transmission system voltage low Code 98 Invalid PCM program Code 99 Invalid PCM program .

Code Description Code 12 No distributor reference pulse (diagnostic test active) Code 13 Oxygen sensor circuit open or no activity Code 14 Engine coolant temp sensor error (high temp indicated) Code 15 Engine coolant temp sensor error (low temp indicated) Code 16 System voltage too low Code 17 Camshaft position sensor error Code 21 Throttle position sensor error (signal high) Code 22 Throttle position sensor error (signal low) Code 23 Intake air temp sensor error (low temp indicated) Code 24 Vehicle speed sensor error (open circuit or no activity) Code 25 Intake air temp sensor error (high temp indicated) Code 26 Quad Driver Module (QDM A) error Code 28 Auto transmission range pressure switch error Code 31 Wastegate solenoid circuit error Code 31 Gear Position Switch (PRNDL) error Code 32 Baro sensor circuit error / EGR circuit Error / MAP sensor signal open Code 33 MAP sensor circuit error (signal high indicating low vacuum) Code 34 MAP sensor circuit error (signal low indicating high vacuum) Code 35 IAC problem or idle error Code 36 MAF sensor error / 24x crankshaft position sensor circuit error / 4T60-E Shifting error Code 37 TCC brake switch circuit error Code 38 TCC brake switch circuit error Code 39 Clutch switch circuit error / Torque converter clutch error Code 41 Ignition control error / MEM-CAL error / C³I Cam Sensor Signal error Code 42 Ignition bypass circuit error Code 43 Knock sensor error Code 44 Oxygen sensor error (lean condition indicated) Code 45 Oxygen sensor error (rich condition indicated) Code 46 Pass-Key II (VATS) system error - circuit out of freq range Code 47 UART (serial data) circuit error Code 51 PROM error / Incorrect MEM-CAL Code 52 Fuel cal-pak incorrect or missing Code 53 System voltage too high Code 53 Digital EGR valve solenoid 1 error Code 54 Fuel pump circuit low voltage / Digital EGR valve solenoid 2 error Code 55 ECM error / Digital EGR valve solenoid 3 error Code 56 Quad Driver Module (QDM B) error Code 57 Boost control error Code 58 Trans fluid temp sensor circuit error (low voltage) / VATS system error Code 59 Trans fluid temp sensor circuit error (high voltage) Code 61 A/C system performance Code 63 Right bank O2 sensor circuit error / MAP sensor circuit signal voltage high (low vacuum indicated) Code 64 Right bank O2 sensor lean exhaust indicated / MAP sensor circuit signal voltage low (high vacuum indicated) Code 65 Right bank O2 sensor rich exhaust indicated Code 66 A/C pressure sensor circuit error (low pressure indicated) Code 67 A/C pressure sensor circuit error Code 68 A/C clutch relay circuit error (shorted to ground) Code 69 A/C clutch relay circuit error (open circuit indicated) / A/C high pressure switch error Code 70 A/C pressure sensor circuit error (high pressure indicated) Code 71 A/C evaporator temp sensor circuit error (low temp indicated) Code 72 VSS signal circuit error Code 73 A/C evaporator temp sensor circuit error (high temp indicated) Code 75 Digital EGR solenoid #1 circuit error Code 76 Digital EGR solenoid #2 circuit error Code 77 Digital EGR solenoid #3 circuit error Code 79 Transmission fluid over temp Code 80 Transmission component slipping Code 82 3x crankshaft position sensor circuit error Code 85 PROM error Code 86 ECM Analog/Digital error Code 87 EEPROM error (flash memory error) Code 90 TCC error Code 93 Transmission pressure control solenoid circuit error Code 96 Transmission system voltage low Code 98 Invalid PCM program Code 99 Invalid PCM program .

Electrical Issues After Replacing the Battery

Late model vehicles have many computerized systems; in most cases, each system is under the basic control of its own computer (module). There can be more than twenty modules on each vehicle and many of these modules have some sort of "learned" memory, which may be lost when the battery is disconnected.

Late model vehicles have many computerized systems; in most cases, each system is under the basic control of its own computer (module). There can be more than twenty modules on each vehicle and many of these modules have some sort of "learned" memory, which may be lost when the battery is disconnected.

GM OBD Trouble Code 12

No Distributor Reference Pulse (Diagnostic Test Active) The Engine Control Module uses the distributor reference pulse to calculate the engine speed. On newer engines, the Crank Shaft Position Sensor performs this function.

No Distributor Reference Pulse (Diagnostic Test Active) The Engine Control Module uses the distributor reference pulse to calculate the engine speed. On newer engines, the Crank Shaft Position Sensor performs this function.

GM OBD Trouble Code 64

Right bank O2 sensor lean exhaust indicated MAP sensor circuit signal voltage low (high vacuum indicated) Depending on the model, code 64 can refer to two different systems. Please choose from one of the above links for specific information on each system.

Right bank O2 sensor lean exhaust indicated MAP sensor circuit signal voltage low (high vacuum indicated) Depending on the model, code 64 can refer to two different systems. Please choose from one of the above links for specific information on each system.

GM OBD Trouble Code 14

Engine Coolant Temperature Sensor Error (High Temp Indicated) The Coolant Temperature sensor sends a signal to the Engine Control Computer based on the temperature of the engine. The ECM uses the information from this sensor to help calculate fuel delivery and spark timing.

Engine Coolant Temperature Sensor Error (High Temp Indicated) The Coolant Temperature sensor sends a signal to the Engine Control Computer based on the temperature of the engine. The ECM uses the information from this sensor to help calculate fuel delivery and spark timing.