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goodwrench9124
goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3420
Experience:  Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
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Just tried to change a radio out in 2006 Chev Cobalt LS. After

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2006 Chevy Cobalt Will Not crank after failed attempt to install radio. Just tried to change a radio out in 2006 Chev Cobalt LS. After installation, we tried to start the car and found out that it would not crank. There is no security light on, nor does it test when the ignition is turned on. Tried to reset for 10min three times no help and no security lights with factory radio installed and working. I did remove lower wire clip (under fuses on passenger side) on the Body Multifunction Computer Connector/Module to see if I could fit a tang for constant power with the battery disconnected. Volt meter measures 12 volts to the starter, and 12 volts from the upper left lower guage (bigger) wire found on the J3 panel I refered to above. Please help
Submitted: 5 years ago.
Category: Chevy
Expert:  goodwrench9124 replied 5 years ago.
Hello, and welcome to JA!! ok let s make sure the basics are ok, there are 2 fuses in the underhood fuse block. checks these 2 fuses, one is the crank relay 30 amp, and the park/neut 10 amp fuse. let me know what you find
Customer: replied 5 years ago.
Hello thanks for helping. Both fuses are good.
Expert:  goodwrench9124 replied 5 years ago.
Ok, good, is this a automatic or a manual trans?
Customer: replied 5 years ago.
auto
Expert:  goodwrench9124 replied 5 years ago.
Ok, one more fuse to check, in the bcm there is a 10 amp fuse marked,HVAC/IP ignition fuse number 16. let me know if this fuse is good?
Customer: replied 5 years ago.
that fuse checks good also
Expert:  goodwrench9124 replied 5 years ago.
Ok, take your voltmeter, while turning the key to crank, check for 12 volts at the ctank fuse in the under hood fuse block. let me know what you come up with?
Customer: replied 5 years ago.
I did not get anything. But I have a question about how I did it. I removed the fuse and put the red lead on one of the clips (that the fuse sits in) and the black lead on ground.
Expert:  goodwrench9124 replied 5 years ago.
ok, reinstall the fuse, look at the fuse real close, there two small metal tabs that stick thru the fuse. use these metal tabs to check for voltage.
Customer: replied 5 years ago.
The crank fuse is a square 30 amp that does not look like a normal rectangular fuse. I removed the fuse and then measured the left pole to ground and got zero and then measured the right pole to ground and got 12.4 volts. I replaced the fuse and removed the top cap and got 12.4 volts to ground with the ignition on and off.
Expert:  goodwrench9124 replied 5 years ago.
ok, the bcm fuse that we checked earlier, havc ign 10 amp make the same test
Customer: replied 5 years ago.
HVAC/IP gets 12 volts when ignition on and HVAC/PK3 has 12 volts all the time.
Expert:  goodwrench9124 replied 5 years ago.

Ok, run down this flow chart, and let me know what you come up with.

 

Ignition OFF, disconnect the harness connector at the PNP switch.

Ignition ON, verify a test lamp illuminates between the ignition circuit terminal 12 and ground.

If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

Ignition OFF, reconnect the harness connector at the PNP switch.

Disconnect the harness connector C1 at the ECM.

Ignition ON, transmission in Park or Neutral, verify a test lamp illuminates between the signal circuit terminal 6 and ground.

If the test lamp does not illuminate, test the signal circuit for an open/high resistance. If the circuit tests normal, test or replace the PNP switch.

Ignition OFF, reconnect the harness connector at the ECM.

Disconnect the CRANK relay.

Ignition ON, transmission in Park or Neutral, verify a test lamp illuminates between the relay coil ignition circuit terminal and ground.

If the test lamp does not illuminate, test the ignition circuit for a short to ground or an open/high resistance.

Verify a test lamp illuminates between the relay switch B+ circuit terminal and ground.

If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the CRANK fuse is open, test the relay controlled output circuit for a short to ground.

Connect a test lamp between the relay coil ignition circuit terminal and the relay coil control circuit terminal.

Important: The engine may begin to crank.

Transmission in Park or Neutral, rotate the ignition cylinder to the crank position and release. The test lamp should turn ON and OFF when changing between the commanded states.

If the test lamp is always ON, test the relay coil control circuit for a short to ground. If the circuit tests normal, replace the ECM.

If the test lamp is always OFF, test the relay coil control circuit for a short to voltage or and open/high resistance. If the circuit tests normal, replace the ECM.

Connect the CRANK relay.

Install a test lamp between the starter S terminal and ground.

Important: The engine may begin to crank.

Transmission in Park or Neutral, rotate the ignition cylinder to the crank position. The test lamp should illuminate.

If the test lamp does not illuminate, test the relay controlled output circuit for an open/high resistance. If the circuit tests normal, test or replace the CRANK relay.

If all circuits test normal, test or replace the starter.

 

 

 

 

graphic

Customer: replied 5 years ago.
I will, it will take a little bit though due to some personal issues. A few questions before I begin. Can I use a voltmeter vs light? Is there a simple way to determine if it is the security measures stopping the crank? I remember from my young boy days to place screwdriver between the starter selenoid poles to check the starter is this applicable in this case?
Expert:  goodwrench9124 replied 5 years ago.

Ok, yes the screwdriver across the starter poles is still a valid test. voltmeter is a very good tool for testing.

 

here is how the teft deterent system works, plus i have added to relearn system, just in case you might to try a relarn.

 

Vehicles with steering column mounted ignition switches have the exciter integral with the TDM, which is located within the steering column. The TDM can learn up to 10 keys (transponder values).

The TDM uses the following inputs: battery voltage, ignition switched voltage and ground circuit. The TDM uses the following outputs: password XXXXX with the engine control module (ECM), start enable/disable via the serial data circuit.

When an ignition key is inserted into the ignition lock cylinder and the ignition is switched ON, the transponder embedded in the head of the key is energized by the exciter coils surrounding the ignition lock cylinder. The energized transponder transmits a signal that contains its unique value, which is received by the TDM. The TDM then compares this value to the learned key code stored in memory. If the value is correct, theTDM sends the challenge to the transponder. Both the transponder and the TDM perform a calculation on the challenge. The TDM then performs one of the following functions:

If both the transponder value and the calculation to the challenge are correct, the TDM will send the start enable message to the ECM via the serial data circuit.
If either the transponders unique value or the calculation to the challenge is incorrect, the TDM will send the start disable message to the ECM via the serial data circuit.
If the TDM is unable to measure the ignition key transponder value for 1 second due to a damaged or missing pellet or a damaged exciter, the TDM will send the start disable message to the ECM via the serial data circuit.

 

 

Use this procedure after replacing any of the following components:

The vehicle keys
The TDM
The ECM

    This procedure is not available on vehicles equipped with export or Canadian configured TDMs.
    When performing the 30-Minute Relearn Procedure, all previously learned keys will be from the TDM memory. Additional keys may be learned after the completeion of the 30-Minute Relearn
    When replacing a TDM with a GM SPO Replacement Part, ensure the procedure to setup a new TDM is performed prior to the 30-Minute Relearn Procedure.

     

With a master vehicle key, turn ON the ignition, with the engine OFF.

Observe the security indicator. After approximately 10 minutes, the telltale will turn OFF.

Turn OFF the ignition, and wait 5 seconds.

Repeat steps 1-3 two more times for a total of 3 cycles or 30 minute The vehicle learns the key transponder information and/or passwords on the ignition switch transition from OFF to RUN. You must turn the ignition OFF before attempting to start the vehicle.

With a master vehicle key, start the vehicle. The vehicle has now learned the key transponder information and/or the ECM has now learned the fuel continue password.

 

Customer: replied 5 years ago.
Do you have any information on the security light. Should it test when moving the key from off to run just like all the other lights? It does this on my tahoe but not on this car. I do not have the light on and I have tried the relearn several times. I am starting the procedure that you sent. Is there a good place to get location of the PNP?
Expert:  goodwrench9124 replied 5 years ago.

I dont believe the security is the problem. if it was the security light should be on. the PNP is the park neutral switch. it is mounted on the transmission where the shift cable connects.

 

graphic

Customer: replied 5 years ago.
found the pnp I got the plug off but the wires and terminals were not identifiable I did get change in voltages between off and start. I know where the ECM is but the C1 connector is not marked. The other parts I could not identify. I do not have any voltage at the relay portion of the starter. I have power available at the starter but nothing energizes the relay. I removed the starter and sent to auto store for testing and starter checked good. There is voltage at the PRK/NEUT fuse, CRNK Fuse, and HVAC IP IGN fuse.
Expert:  goodwrench9124 replied 5 years ago.
sorry for the delay, by all the tests that you have run, it is looking like a problem with the pcm. the pcm grounds the crank relay to engernize the starter. but it would be almost impossible to know for sure with a scan tool that reads real time data. with a scan tool, you can look at the pcm data and look for a crank request. the good news if the pcm is the fault, it is covered for 8 years and 80,000 miles.
goodwrench9124, ASE Certified Technician
Category: Chevy
Satisfied Customers: 3420
Experience: Ase Master Certified, GM Master Certified Tech. Awarded GM Top performer, Hybrid certified
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