20 Most Recent
- Page 4 Questions & Answers
2002 chevy trailblazer and it will not crank or start and the key has gotten stuck in the ignition. I also got a jumpstart and it still didn't start. What is wrong, Please?
Could be a number of thing's , can you do automotive electrical testing ? Do you know if starting is PCM / ECM controlled or BCM controlled ? Do you know what these are ? BCM - body control module , PCM/ECM - engine computer !
Moving the ignition switch to the START position sends a 12-volt signal to the engine control module (ECM)/powertrain control module (PCM) Crank Request circuit. The ECM/PCM verifies that the transmission is in the PARK or NEUTRAL position. With the transmission in Park, voltage flows through the Park/Neutral position switch and feeds the starter relay coil. The PCM then grounds the control circuit of the starter relay. When the starter relay is energized it allows battery positive voltage to the starter solenoid S terminal. On some vehicles the starter will continue to crank the engine with the key released until it starts or the crank command has timed out to prevent excessive heat build up in the starter circuitry or the ECM/PCM receives an engine run flag.
Circuit Description (BCM Controlled)
Moving the ignition to the START position signals the body control module (BCM) that engine crank has been requested. The BCM verifies that theft is not active and sends a serial data message to the powertrain control module (PCM) requesting engine start. The BCM also energizes the RUN/CRANK RELAY. When the RUN/CRANK RELAY switch side closes, and the vehicle is in Park or Neutral or with the clutch is fully depressed, if equipped, supplies voltage to the starter relay coil. The PCM verifies the transmission is in Park or Neutral and the clutch is fully depressed, if equipped. The PCM will then ground the control circuit of the starter relay, closing the switch supplying voltage to the starter solenoid. On some vehicles the starter will continue to crank the engine with the key released until it starts of the crank command has timed out to prevent excessive heat build up in the starter circuitry or the PCM receives an engine run flag.
Do you know what a park neutral safety switch is ? What do you mean key stuck in ignition ? Can't turn the key to off position , or you can an the key will not come out ?
Your best bet , take it to a qualified repair shop .
on Apr 06, 2017
My 2002 trailblazer cranks but wont start checked fuses relays and battery
The first thing to do is check for fuel pressure, the fuel pressure test port is on the top of the engine in the pipe that supplies fuel and sits over the fuel injectors, it looks kind of like a tire fill valve. A quick way to see if fuel is the problem is to buy a can of spray starting fluid, spray it into the engine air intake hose while the engine is cranked over, if it starts then shuts off you have a failed fuel pump or fuel pump circuit problem. Below you will find a link to the wiring diagrams to check the fuel pump wiring circuits. If fuel is ok then run a fault code test on the engine control module. You will need an OBD2 system code reader, you can borrow one from most chain auto parts stores. Read the fault code and then Google them for help with there meanings. http://bbbind.com/free_tsb.html
on Mar 30, 2017
Have 02 trailblazer loses power going uphill
First have the engine control module (PCM) scanned for fault codes, next if that yields no results have the fuel pressure checked under a load while driving and duplicating the power loss, you may have a failing fuel pump. The least likely possibility is that the exhaust system is somehow restricted, in that case you would need a shop to do what is called a exhaust backpressure test.
on Mar 23, 2017
Loss of engine power, loud whistling noise
Exhaust manifold leak? That's not common. You talking about the VVT near the manifold at the top of engine above the power steering pump? Yes indeed, AC Delco is the only one our engines love. 41-103. Obviously you have P0304, what other codes?
on Mar 16, 2017
Throttle position sensor problems
reduced engine power has to do with the electronic throttle control or drive by wire . All electronic wires under the dash on the gas pedal , electric motor on the throttle body . DTC'S - diagnostic trouble codes stored in the computer . Take it to the dealer .
on Mar 04, 2017
2002 trialblazer rear window wiper inop. changed switch and motor. no power to motor. cannot find relay nor fuse
There are something's involved that you are not aware of , or familiar with . Electronic control modules .
Rear Wiper/Washer System Controls
• Body control module (BCM)
• Liftgate control module (LGM)
• Rear wiper/washer switch
Do you know what a serial data network is ?
Rear Wiper/Washer System Operation
The rear window wiper/washer switch is an input to the BCM. The requested rear wiper mode is sent to the liftgate control module (LGM) by the BCM as a message on the serial data circuit, and the rear window wiper motor is controlled by the LGM. The switch power circuit to the rear wiper/washer switch is a 12-volt reference supplied by the BCM during ignition on, accessory or RAP power modes. The rear wiper/washer switch is a series of resistors and the switch position is determined by the voltage of the rear wiper/washer switch signal circuit to the BCM. The rear wiper/washer switch has continuity at all times and the BCM expects a rear wiper/washer switch signal voltage in all switch positions including OFF. The rear wiper motor is supplied battery positive voltage and ground. The LGM controls rear wiper motor operation through the rear wiper motor control circuit. The rear wiper motor control circuit is supplied a battery positive reference voltage by the rear wiper motor module and is pulse width modulated to ground by the LGM. The duty cycle of the pulse width modulation determines the rear wiper motor operating mode. The liftglass and liftgate ajar switches are inputs to the LGM and must be in an inactive state in order for rear wiper washer system operation to be enabled. When an ajar switch is active the LGM suspends wiper motor operation directly and sends the ajar switch status messages over the serial data circuit enabling the BCM to suspend washer pump operation. The rear window washer pump is controlled by the BCM through the rear washer relay. Battery positive voltage is supplied to the coil and switch sides of the rear washer relay. When the rear window wash request is active the BCM energizes the relay by grounding the relay coil through the rear washer relay control circuit. When the relay is energized battery positive voltage to the relay switch is supplied to the washer pump control circuit.
Your best bet , take it to a qualified repair shop and have it checked for DTC'S - diagnostic trouble codes .
DTC B1017 or B3970
The rear wiper motor is supplied battery positive voltage and ground. The liftgate control module controls rear wiper motor operation through the rear wiper motor control circuit. The rear wiper motor control circuit is supplied a battery positive reference voltage by the rear wiper motor module and is pulse width modulated to ground by the liftgate control module. The duty cycle of the pulse width modulation determines the rear wiper motor operating mode.
Turn the ignition ON.
Operate the rear wiper switch through all the switch positions.
Does the rear window wiper operate normally?
YES - Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems
NO - Go to Step 3
Install a scan tool.
Display the liftgate control module data list.
Observe the following parameters while operating the respective switches. Refer to Scan Tool Data List for typical values.
• Liftgate Ajar Switch
• Liftglass Ajar Switch
Did the scan tool indicate the correct switch positions?
Go to Step 4
Go to Courtesy Lamps Inoperative in Lighting Systems
Observe the requested rear wiper parameter in LGM data list.
Operate the rear wiper switch through all the switch positions.
Does the scan tool indicate the correct requested rear wiper parameter in relation to the switch position?
Go to Step 5
Go to Step 6
on Feb 06, 2017
Not finding what you are looking for?