Need help jump starting a 2005
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Intermediate
Joined: Feb 2025
Posts: 39
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Thread Starter
Intermediate
Joined: Feb 2025
Posts: 39
Likes: 3
Clutch pedal...look at the wiring diagram....we can see if you are getting power to the ECM fuse at the BCM when the start button is pushed...you will need 2 people to do this...use a test light at the fuse....we may need to check if the backup antenna is good...you will need a voltmeter for this using the AC VOLTAGE scale.
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Joined: Sep 2013
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From: Cape Coral, Florida
OK, it's good that you see 12 volts at the ECM fuse when you push the start button...it looked like the green start light was on in your video when trying to start the car...remove crank relay 43 and probe "C13" in the picture when trying to start the car...the rear terminal closest to the fender...you should see 12 volts or the test light should light there when trying to start the car... if the car were in ACCY mode the ECM fuse would not have been powered.
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Thread Starter
Intermediate
Joined: Feb 2025
Posts: 39
Likes: 3
OK, it's good that you see 12 volts at the ECM fuse when you push the start button...it looked like the green start light was on in your video when trying to start the car...remove crank relay 43 and probe "C13" in the picture when trying to start the car...the rear terminal closest to the fender...you should see 12 volts or the test light should light there when trying to start the car... if the car were in ACCY mode the ECM fuse would not have been powered.
Last edited by cs641; Feb 16, 2025 at 03:41 PM.
Moderator, Tech Contributor
Joined: Sep 2013
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From: Cape Coral, Florida
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,595
Likes: 4,055
From: Cape Coral, Florida
Right one !!...if you have 12 volts at the ECM fuse when starting the only thing between that fuse and the crank relay is the clutch switch but you said you saw 12 volts there...remove the connector off the switch and put your DVOM on ohms and see if you have continuity between the 2 terminals when you push the clutch switch down with your finger....you can check if you have continuity between the purple/white wire at the clutch switch and terminal C13 at the crank relay...are you SURE you are contacting that terminal ??
Last edited by C5 Diag; Feb 16, 2025 at 03:55 PM.
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From: Cape Coral, Florida
Moderator, Tech Contributor
Joined: Sep 2013
Posts: 15,595
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From: Cape Coral, Florida
Hold on !!...I'm looking at the crank relay on my 08 vs your 05...my starter enable relay control is "power side switched" !!...your 05 is looking for a ground at C13...crap !!...you have a test light ??...you need one to make this less confusing for you...test the terminal caddy corner from C13...would be A14 in the picture...with test light connected to battery POSITIVE the test light should illuminate when probing A14 and you trying to start the car...sorry...power from the clutch switch is powering the relay coil and when the PCM supplies the GROUND the relay will energize and the car will start.
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From: Cape Coral, Florida
Circuit Description
Pressing the Start switch sends a discrete input to the body control module (BCM) notifying it that engine start has been requested. The BCM then verifies that the brake pedal has been depressed with a discrete input from the break pedal switch and that the key fob, with the correct code, is in the vehicle. After this information has been verified the BCM grounds the control side of the RUN/CRANK Relay closing the switch side of it and allowing battery positive voltage to flow from the BATT 3 fuse through the RUN/CRANK Relay switch, ECM Fuse to the battery positive voltage side of the Crank Relay Coil. The BCM also sends a high speed GMLAN message to the ECM requesting engine start. The ECM will then verify that the internal mode switch (IMS) is in Park of Neutral. After this has been verified the ECM grounds the control circuit of the CRANK Relay closing the CRANK Relay Switch Circuit and allowing battery positive voltage to flow through the STARTER Fuse, the CRANK Relay switch to the S terminal of the Starter solenoid cranking the engine. Ground is supplied through the engine block.
Pressing the Start switch sends a discrete input to the body control module (BCM) notifying it that engine start has been requested. The BCM then verifies that the brake pedal has been depressed with a discrete input from the break pedal switch and that the key fob, with the correct code, is in the vehicle. After this information has been verified the BCM grounds the control side of the RUN/CRANK Relay closing the switch side of it and allowing battery positive voltage to flow from the BATT 3 fuse through the RUN/CRANK Relay switch, ECM Fuse to the battery positive voltage side of the Crank Relay Coil. The BCM also sends a high speed GMLAN message to the ECM requesting engine start. The ECM will then verify that the internal mode switch (IMS) is in Park of Neutral. After this has been verified the ECM grounds the control circuit of the CRANK Relay closing the CRANK Relay Switch Circuit and allowing battery positive voltage to flow through the STARTER Fuse, the CRANK Relay switch to the S terminal of the Starter solenoid cranking the engine. Ground is supplied through the engine block.