Very Strange "Car won't start sometimes" problem
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
The Ignition Switch is divided into three different segments.
The: KEY LOCK CYLINDER / VATS SENSOR part, The ELECTRICAL SWITCH part & The MECHANICAL PART that moves the actual pins that cause the ignition switch contacts contacts to open and shut.
Hanging extra weight on the key chain WILL NOT effect the electrical switches. In fact, you can remove the KEY LOCK CYLINDER / VATS SENSOR part from the rest of the switch and turn the switch with a flat blade screwdriver to the different switch positions
That said, extra weight can put added stress on the cylinder lock and the VATS Sensor on the end of the key cylinder.
If you are having electrical issues with the switch, CHANGE THE SWITCH with a new one. The Lock Cylinder / VATS part can be easily removed and put into the new switch.
The: KEY LOCK CYLINDER / VATS SENSOR part, The ELECTRICAL SWITCH part & The MECHANICAL PART that moves the actual pins that cause the ignition switch contacts contacts to open and shut.
Hanging extra weight on the key chain WILL NOT effect the electrical switches. In fact, you can remove the KEY LOCK CYLINDER / VATS SENSOR part from the rest of the switch and turn the switch with a flat blade screwdriver to the different switch positions
That said, extra weight can put added stress on the cylinder lock and the VATS Sensor on the end of the key cylinder.
If you are having electrical issues with the switch, CHANGE THE SWITCH with a new one. The Lock Cylinder / VATS part can be easily removed and put into the new switch.
Instructor
Joined: Nov 2008
Posts: 147
Likes: 8
From: Nashville, TN
Just a bump on this thread as it gave me quite a few options to check on my intermittent no start I've been having for months. 2004 z06 coming up on 250K
Problem 1:Original symptom, turn key to start, car would crank once, then nothing. Do it again, would fire up immediately. This started about a year ago. Happens probably 8 out of 10 times.
Problem 2: About 3 months ago, I was getting the infamous "Pull key wait 10 seconds". Install the LCM5 module. Car would start normally. (still get the message every so often, think I need to do the optional brown wire step)
Problem 3: About a month ago, turn key to start, no crank, no click from starter, just everything else would light up. Would try about 10-15 times and finally would fire up.
A combination of problems 1 and 3 led me to believe ignition switch is going bad. Replaced switch over the weekend, still same problem 3, no crank, no click.
Bought a starter, and was about to start tearing it apart, but then remembered on my dad's truck, that just a relay needed to be replaced. Dug thru this thread at all the recommendations.
Solution 1: Jumped red wire to purple wire on TDR relay, motor fired right up. So not the starter, returned it to get money back. Replaced the TDR relay. Still same problem.
Solution 2: While key to start position and held, slowly released the clutch and motor fired right up. Replaced the clutch safety switch. Problem resolved.
Ignition switch = $100 (already installed, although probably didn't need to replace)
TDR relay= $20 (already installed, although probably didn't need to replace)
Clutch safety switch = $10
Starter = $200 returned for refund, big save there
This thread was very helpful, so thank you to all the past responses. I still haven't figured out Problem 1, probably is solenoid on the starter. But least I can just turn key twice to get it to start.
Problem 1:Original symptom, turn key to start, car would crank once, then nothing. Do it again, would fire up immediately. This started about a year ago. Happens probably 8 out of 10 times.
Problem 2: About 3 months ago, I was getting the infamous "Pull key wait 10 seconds". Install the LCM5 module. Car would start normally. (still get the message every so often, think I need to do the optional brown wire step)
Problem 3: About a month ago, turn key to start, no crank, no click from starter, just everything else would light up. Would try about 10-15 times and finally would fire up.
A combination of problems 1 and 3 led me to believe ignition switch is going bad. Replaced switch over the weekend, still same problem 3, no crank, no click.
Bought a starter, and was about to start tearing it apart, but then remembered on my dad's truck, that just a relay needed to be replaced. Dug thru this thread at all the recommendations.
Solution 1: Jumped red wire to purple wire on TDR relay, motor fired right up. So not the starter, returned it to get money back. Replaced the TDR relay. Still same problem.
Solution 2: While key to start position and held, slowly released the clutch and motor fired right up. Replaced the clutch safety switch. Problem resolved.
Ignition switch = $100 (already installed, although probably didn't need to replace)
TDR relay= $20 (already installed, although probably didn't need to replace)
Clutch safety switch = $10
Starter = $200 returned for refund, big save there
This thread was very helpful, so thank you to all the past responses. I still haven't figured out Problem 1, probably is solenoid on the starter. But least I can just turn key twice to get it to start.
Instructor
Joined: Mar 2016
Posts: 231
Likes: 14
From: NY
Just to add to the discussion for those who don't full understand. If the car won't crank over and the Security light is on and DTCs set, then the problem is related to the PASS-Key system - bad key pellet or ignition switch not reading the key pellet. If the car will not crank and there is no Security light showing or DTCs set, then it's related to the TDR, starter solenoid, clutch switch, or possibly a bad ground in the starting system somewhere.
Instructor
Joined: Mar 2016
Posts: 231
Likes: 14
From: NY
Just to add to the discussion for those who don't full understand. If the car won't crank over and the Security light is on and DTCs set, then the problem is related to the PASS-Key system - bad key pellet or ignition switch not reading the key pellet. If the car will not crank and there is no Security light showing or DTCs set, then it's related to the TDR, starter solenoid, clutch switch, or possibly a bad ground in the starting system somewhere.
Just a bump on this thread as it gave me quite a few options to check on my intermittent no start I've been having for months. 2004 z06 coming up on 250K
Problem 1:Original symptom, turn key to start, car would crank once, then nothing. Do it again, would fire up immediately. This started about a year ago. Happens probably 8 out of 10 times.
Problem 2: About 3 months ago, I was getting the infamous "Pull key wait 10 seconds". Install the LCM5 module. Car would start normally. (still get the message every so often, think I need to do the optional brown wire step)
Problem 3: About a month ago, turn key to start, no crank, no click from starter, just everything else would light up. Would try about 10-15 times and finally would fire up.
A combination of problems 1 and 3 led me to believe ignition switch is going bad. Replaced switch over the weekend, still same problem 3, no crank, no click.
Bought a starter, and was about to start tearing it apart, but then remembered on my dad's truck, that just a relay needed to be replaced. Dug thru this thread at all the recommendations.
Solution 1: Jumped red wire to purple wire on TDR relay, motor fired right up. So not the starter, returned it to get money back. Replaced the TDR relay. Still same problem.
Solution 2: While key to start position and held, slowly released the clutch and motor fired right up. Replaced the clutch safety switch. Problem resolved.
Ignition switch = $100 (already installed, although probably didn't need to replace)
TDR relay= $20 (already installed, although probably didn't need to replace)
Clutch safety switch = $10
Starter = $200 returned for refund, big save there
This thread was very helpful, so thank you to all the past responses. I still haven't figured out Problem 1, probably is solenoid on the starter. But least I can just turn key twice to get it to start.
Problem 1:Original symptom, turn key to start, car would crank once, then nothing. Do it again, would fire up immediately. This started about a year ago. Happens probably 8 out of 10 times.
Problem 2: About 3 months ago, I was getting the infamous "Pull key wait 10 seconds". Install the LCM5 module. Car would start normally. (still get the message every so often, think I need to do the optional brown wire step)
Problem 3: About a month ago, turn key to start, no crank, no click from starter, just everything else would light up. Would try about 10-15 times and finally would fire up.
A combination of problems 1 and 3 led me to believe ignition switch is going bad. Replaced switch over the weekend, still same problem 3, no crank, no click.
Bought a starter, and was about to start tearing it apart, but then remembered on my dad's truck, that just a relay needed to be replaced. Dug thru this thread at all the recommendations.
Solution 1: Jumped red wire to purple wire on TDR relay, motor fired right up. So not the starter, returned it to get money back. Replaced the TDR relay. Still same problem.
Solution 2: While key to start position and held, slowly released the clutch and motor fired right up. Replaced the clutch safety switch. Problem resolved.
Ignition switch = $100 (already installed, although probably didn't need to replace)
TDR relay= $20 (already installed, although probably didn't need to replace)
Clutch safety switch = $10
Starter = $200 returned for refund, big save there
This thread was very helpful, so thank you to all the past responses. I still haven't figured out Problem 1, probably is solenoid on the starter. But least I can just turn key twice to get it to start.
Solution 2: While key to start position and held, slowly released the clutch and motor fired right up. Replaced the clutch safety switch. Problem resolved.
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
You can avoid ALL of the confusion by Finding the Theft Deterrent Relay (TDR) and using a multimeter to measure ALL of the voltages on the TDR relay contacts. The TDR relay is the HEART of the STARTER CIRCUIT. Funny,, There are only F O U R wires on the TDR relay and that's all you need to properly troubleshoot most non CRANK problems. Its in the passengers footwell, behind the toe board panel, above the BCM on the fire wall.
PURPLE wire: Wire that goes to and powers the starter Solenoid.
RED wire: 12VDC (60 amp) "full time" power from battery.
Yellow Wire. Reads 12 VDC when the ignition switch is turned to the START position & (clutch depressed OR "AUTO TRANS" is in Park or Neutral)
Yellow/Black stripe BCM Security wire (Goes to chassis ground by a driver transistor in the BCM when all vehicle BCM security requirements are met.) Completes the circuit so the TDR relay coil can energize by the 12 VDC voltage from the YELLOW wire and when the relay coil energizes it connects the RED 12VDC 60 amp circuit contact to the PURPLE solenoid hot wire contact and runs the starter motor. You can GROUND the Yellow/Black stripe wire to chassis ground to eliminate the BCM security requirements as a test.
PLEASE don't blindly state: My car wont start.
PLEASE state that:
1. The Starter will not crank over the engine.
2. The starter Cranks Over the engine over but the engine will not run.
3. Any other amplifying details.
BC
PURPLE wire: Wire that goes to and powers the starter Solenoid.
RED wire: 12VDC (60 amp) "full time" power from battery.
Yellow Wire. Reads 12 VDC when the ignition switch is turned to the START position & (clutch depressed OR "AUTO TRANS" is in Park or Neutral)
Yellow/Black stripe BCM Security wire (Goes to chassis ground by a driver transistor in the BCM when all vehicle BCM security requirements are met.) Completes the circuit so the TDR relay coil can energize by the 12 VDC voltage from the YELLOW wire and when the relay coil energizes it connects the RED 12VDC 60 amp circuit contact to the PURPLE solenoid hot wire contact and runs the starter motor. You can GROUND the Yellow/Black stripe wire to chassis ground to eliminate the BCM security requirements as a test.
PLEASE don't blindly state: My car wont start.
PLEASE state that:
1. The Starter will not crank over the engine.
2. The starter Cranks Over the engine over but the engine will not run.
3. Any other amplifying details.
BC
Tech Contributor
Joined: Jan 2007
Posts: 19,448
Likes: 1,155
From: Dyer, IN
You can avoid ALL of the confusion by Finding the Theft Deterrent Relay (TDR) and using a multimeter to measure ALL of the voltages on the TDR relay contacts. The TDR relay is the HEART of the STARTER CIRCUIT. Funny,, There are only F O U R wires on the TDR relay and that's all you need to properly troubleshoot most non CRANK problems. Its in the passengers footwell, behind the toe board panel, above the BCM on the fire wall.
PURPLE wire: Wire that goes to and powers the starter Solenoid.
RED wire: 12VDC (60 amp) "full time" power from battery.
Yellow Wire. Reads 12 VDC when the ignition switch is turned to the START position & (clutch depressed OR "AUTO TRANS" is in Park or Neutral)
Yellow/Black stripe BCM Security wire (Goes to chassis ground by a driver transistor in the BCM when all vehicle BCM security requirements are met.) Completes the circuit so the TDR relay coil can energize by the 12 VDC voltage from the YELLOW wire and when the relay coil energizes it connects the RED 12VDC 60 amp circuit contact to the PURPLE solenoid hot wire contact and runs the starter motor. You can GROUND the Yellow/Black stripe wire to chassis ground to eliminate the BCM security requirements as a test.
PLEASE don't blindly state: My car wont start.
PLEASE state that:
1. The Starter will not crank over the engine.
2. The starter Cranks Over the engine over but the engine will not run.
3. Any other amplifying details.
BC
PURPLE wire: Wire that goes to and powers the starter Solenoid.
RED wire: 12VDC (60 amp) "full time" power from battery.
Yellow Wire. Reads 12 VDC when the ignition switch is turned to the START position & (clutch depressed OR "AUTO TRANS" is in Park or Neutral)
Yellow/Black stripe BCM Security wire (Goes to chassis ground by a driver transistor in the BCM when all vehicle BCM security requirements are met.) Completes the circuit so the TDR relay coil can energize by the 12 VDC voltage from the YELLOW wire and when the relay coil energizes it connects the RED 12VDC 60 amp circuit contact to the PURPLE solenoid hot wire contact and runs the starter motor. You can GROUND the Yellow/Black stripe wire to chassis ground to eliminate the BCM security requirements as a test.
PLEASE don't blindly state: My car wont start.
PLEASE state that:
1. The Starter will not crank over the engine.
2. The starter Cranks Over the engine over but the engine will not run.
3. Any other amplifying details.
BC
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