Jul 202016

1988 Chevy S-10I have a 1988 Chevy s-10 v6 2.8l 4×4 ext cab with 120,000 miles on it and no spark. Great truck, daily driver never had a problem with it.  I went to the store, came out and it would not start. It cranked like crazy but would not start. I had it towed home. I got up early took the battery post off and put them back on and the truck fired right up with no problem. It cranked a little longer but it fired up. I cut it off, came back out and it would not fire. So I took a spark plug wire off and noticed it was not getting any fire from the plug wires. So I took the ignition module off and took it to Oreilys and they tested it. They said it was bad so replaced the ignition module and still no fire. Then I replaced ignition coil still no spark. I can hear the fuel pump kicking on but I don’t see gas spraying out of the injectors when I crank the engine. I have not tested for fuel pressure. The only other thing I can think of is it being the distributor cap not getting good fire to the plug wires. Any advice will be helpful thanks.


First thing to check would be the 10 amp ECM 1 Fuse. This fuse when blown would keep the PCM from allowing injector pulse and distributor spark. The 10 amp ECM B fuse if blown would not allow fuel pump operation. If the fuses check out OK then you are left with the Pick up coil in the distributor that signals the ECM and then the ECM itself. Of cousre this is assuming the wiring harness is also GOOD. All of which could cause a no spark situation.

1988 Chevy s10 V6 engine wiring diagram for no spark

The heart of the electronic control system which is found on most vehicles covered by this manual is a computer control module. The module gathers information from various sensors, then controls fuel supply and engine emission systems. Most vehicles are equipped with an Engine Control Module (ECM) which, as its name implies, controls the engine and related emissions systems. Some ECMs may also control the Torque Converter Clutch (TCC) on automatic transmission vehicles or the manual upshift light on manual transmission vehicles. Later model vehicles may be equipped with a Powertrain Control Module (PCM) or a Vehicle Control Module (VCM). Both of these are similar to the original ECMs, but are designed to control additional systems as well. The PCM may control the manual transmission shift lamp or the shift functions of the electronically controlled automatic transmission. The VCM is used to control the manual shift lamp and electronic brake control functions.

Regardless of the name, all computer control modules are serviced in a similar manner. Care must be taken when handling these expensive components in order to protect them from damage. Carefully follow all instructions included with the replacement part. Avoid touching pins or connectors to prevent damage from static electricity.

All of these computer control modules contain a Programmable Read Only Memory chip or CALPAK that contains calibration information which is particular to the vehicle application. This chip is not supplied with a replacement module and must be transferred to the new module before installation. Late model vehicles equipped with a VCM utilize both a PROM chip and an Electronically Erasable Programmable Read Only Memory (EEPROM) which must be reprogrammed after installation.

To prevent the possibility of permanent control module damage, the ignition switch MUST always be OFF when disconnecting power from or reconnecting power to the module. This includes unplugging the module connector, disconnecting the negative battery cable, removing the module fuse or even attempting to jump your dead battery using jumper cables.

Jul 132016

1999 Chevy CorvetteHi, my 1999 Chevy Corvette stalls when I go in reverse or forward, it idles just fine. It usually happens when I park somewhere uneven. If I don’t use it for a while it works just fine.


There are no recalls or TSB’s for this issue. I would start by pulling any stored codes that may be present. Also try running the fuel out and putting in some high octane from a premium fueling station.

An Ignition control circuit that is open, grounded, or short to voltage will set an ignition control circuit DTC. If a fault occurs in the IC output circuit when the engine is running, the engine will experience a misfire. DTCs P0351-P0358 will set when a malfunction is detected with an Ignition Control circuit. When an Ignition control DTC sets, the PCM will disabled the injector for the appropriate cylinder.

The Chevy Corvette PCM uses information from the engine coolant temperature sensor in addition to RPM to calculate spark advance values as follows:

  • High RPM = more advance
  • Cold engine = more advance
  • Low RPM = less advance
  • Hot engine = less advance

Therefore, detonation may be caused by high resistance in the engine coolant temperature sensor circuit. Poor performance may be caused by low resistance in the engine coolant temperature sensor circuit.

If the engine cranks but will not run or immediately stalls, Engine Cranks But Will Not Run diagnostic table must be used to determine if the failure is in the ignition system or the fuel system. If DTC P0300, P0341, P0342, P0343, P0335, P0336 is set, the appropriate diagnostic trouble code table must be used for diagnosis.


 Never pierce a secondary ignition wire or boot for any testing purposes.

Be careful not to damage the secondary ignition wires or boots when servicing the ignition system. Rotate each boot to dislodge it from the plug or coil tower before pulling it from either a spark plug or the ignition coil. Future problems are guaranteed if pinpoints or test lights are pushed through the insulation for testing.

Jul 112016

2007 Chevy 1500I have Code P0641 on my 2007 Chevy 1500, Where should I start?


Check your connections at the computer and the wiring harness. If all checks out you will most likely need to replace the ECM itself.

P0641 CHEVROLET – 5 Volt Reference Voltage Incorrect

The control module has 2 internal 5-volt reference buses called 5-volt reference 1 and 5-volt reference 2 . Each reference bus provided 5-volt reference circuit for more than one sensor. Therefore, a fault condition on one 5-volt reference circuit will affect the other 5-volt reference circuits connected to the reference bus. The control module monitors the voltage on the 5-volt reference buses.

When is the code detected?
The Engine Control Module (ECM) has detected the sensor 5 volt reference circuit voltage is higher or lower than expected
Code P0641 Possible causes
– Faulty Engine Control Module (ECM)
– ECM harness is open or shorted
– ECM circuit poor electrical connection
– Shorted sensor on 5 volt circuit

ECM – Engine Control Module Replacement 2007 Chevy 1500

Jul 072016

1994 Chevy 6.5 turbo dieselWould a bad vacuum pump make the pickup spit, sputter, smoke and loose power. Or is it the catalytic converter?



The vacuum pump on the 6.5L engine provides vacuum for operating emission controls, cruise control and heater and A/C servos.

That being said, I do not think the vacuum pump has anything to do with the engine spitting and sputtering or the loss of power.

If the catalytic converter was clogged, it could cause the issues you are having.

Jun 272016

1996 Chevy Silverado 1500Recently bought a 1996 Chevy Silverado 1500 truck and noticed brake lights/turn signals are not working. Replaced brake light switch and then the turn signal switch neither one is working. What should I check next????


The bulbs. The brake light bulb and turn signal bulb are the same. Check for good ground and then for battery voltage at the socket. If no battery voltage is seen, check the fuses and relay. If they check OK, trace the wiring to and from the brake switch and repair as needed. I will supply you with a brake light wiring diagram to help you trace the wiring.

Brake light wiring diagram 1996 Chevy Silverado 1500

Jun 272016

2006 Chevy Monte Carlodoes not shift out of 1st gear. no problems with reverse park or neutral.


If the transmission fluid is full and clean, could be an issue with a shift solenoid. There may be a code stored int eh computer that wouldn’t necessarily turn on the check engine light. Have any codes pulled and post them below.

How the transmission works in a 2006 Chevy Monte Carlo

The 4T65-E is a fully automatic front wheel drive electronically controlled transmission. The 4T65-E provides four forward ranges including overdrive. The PCM controls shift points by means of two shift solenoids. A vane-type oil pump supplies the oil pressure. The PCM regulates oil pressure by means of a pressure control solenoid valve.

All vehicles equipped with a 4T65-E transmission have an electronically controlled capacity clutch (ECCC) system. In the ECCC system, the pressure plate does not fully lock to the torque converter cover. It is instead, precisely controlled to maintain a small amount of slippage between the engine and the turbine, reducing driveline torsional disturbances.

You can operate the transmission in any one of the following seven modes:

    • P — Park position prevents the vehicle from rolling either forward or backward. For safety reasons, use the parking brake in addition to the park position.
    • R — Reverse allows the vehicle to be operated in a rearward direction.
    • N — Neutral allows the engine to be started and operated while driving the vehicle. If necessary, you may select this position in order to restart the engine with the vehicle moving.
    • D — Overdrive is used for all normal driving conditions. Overdrive provides four gear ratios plus a converter clutch operation. Depress the accelerator in order to downshift for safe passing.
    • 3 — Drive position is used for city traffic and hilly terrain. Drive provides three gear ranges and drive range prevents the transmission from operating in fourth gear. Depress the accelerator in order to downshift.
    • 2 — Manual Second provides two gear ratios under most operating conditions. Manual Second provides acceleration and engine braking. Select this range at any vehicle speed, but the transmission will not downshift into Second gear until the vehicle speed drops below approximately 100 km/h (62 mph)
    • 1 — Manual Lo provides maximum engine braking. You may also select this range at any vehicle speed, but the transmission will not downshift into First gear until the vehicle speed drops below approximately 60 km/h (37 mph).
Jun 202016

power seat 1996 Chevy LuminaI have a driver side power seat that will track forward but not back. Is that the motor or is that the switch?


It could be either of the two or the wiring harness and or connection at the power seat. May also be an obstruction in the way causing it to bind.  You will need to use a multi-meter and do a little testing. Check for power being applied to the motor when the seat will not move. If power is being applied then the motor is bad or there is something causing it to bind. Remove the motor and test it again. If no power is getting to the motor, trace the wiring back to the switch and repair as needed.

Power Seat 1996 Chevy Lumina Wiring Diagram