2005 2500 Suburban No Crank
#21
CF Active Member
Greetings, not sure if I was supposed to remove the blue and green connectors from the PCM to perform the above diagnostic steps, but I did. ...As it worked out, I removed the Blue connector first and the green connector was still attached. So blue connector, terminal 39 had 12 volts in the RUN position. It also had 12v in the start position.
The crank test proved that the starter circuit (ignition switch, IGN E fuse, PNP switch, starter relay, starter) is good.
Lack of voltage at PCM Green 59 shows that there is a bad connection between the CRANK fuse and the PCM connector.
Or, a bad fuse, did you check the CRANK fuse with a meter?
With the PCM connectors plugged in try applying 12 volts to the green #59 from the back of the connector with a small wire or paper clip. If the car starts this will prove the PCM is good. If good, now comes the fun part , trying to follow the purple wire back to the fuse block to find where you loose the 12 v start signal. The other end wire should be at the fuse block's 68 pin, black connector, pin F3
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mountainmanjoe (May 28th, 2024)
#22
this wire should be on the same circuit as the CRANK fuse that you tested earlier. So if power isn't getting to the PCM, that means there is a fault somewhere between the fuse and this connector.
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a55bruce (May 28th, 2024)
#23
The connector needs to be plugged in and the crank circuit has to be good (it's not).
Great testing. I was intending for you to leave the connectors plugged in. You got the info we need to go on. No need to retest.
The crank test proved that the starter circuit (ignition switch, IGN E fuse, PNP switch, starter relay, starter) is good.
Lack of voltage at PCM Green 59 shows that there is a bad connection between the CRANK fuse and the PCM connector.
Or, a bad fuse, did you check the CRANK fuse with a meter?
With the PCM connectors plugged in try applying 12 volts to the green #59 from the back of the connector with a small wire or paper clip. If the car starts this will prove the PCM is good. If good, now comes the fun part , trying to follow the purple wire back to the fuse block to find where you loose the 12 v start signal. The other end wire should be at the fuse block's 68 pin, black connector, pin F3
Great testing. I was intending for you to leave the connectors plugged in. You got the info we need to go on. No need to retest.
The crank test proved that the starter circuit (ignition switch, IGN E fuse, PNP switch, starter relay, starter) is good.
Lack of voltage at PCM Green 59 shows that there is a bad connection between the CRANK fuse and the PCM connector.
Or, a bad fuse, did you check the CRANK fuse with a meter?
With the PCM connectors plugged in try applying 12 volts to the green #59 from the back of the connector with a small wire or paper clip. If the car starts this will prove the PCM is good. If good, now comes the fun part , trying to follow the purple wire back to the fuse block to find where you loose the 12 v start signal. The other end wire should be at the fuse block's 68 pin, black connector, pin F3
You gentlemen know what they say about a picture!
Nest in the bottom.
I put power to the purple wire #59' green connector and it fired right up. I went looking and here is what I found. I had suspected mice early on, but I didn't see any obvious sign. I obviously didn't know where to look. Under the fuse box is an ideal nesting place for those rascals. So thank you both from the bottom of my heart! I know the neighbor lady thanks you also. Wish I could return the favor someday. TK.
The following 2 users liked this post by Ted K:
jfmorris (May 30th, 2024),
mountainmanjoe (May 29th, 2024)
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Ted K (May 29th, 2024)
#25
Congrats!
Finding that was relatively painless.
Repair doesn't look like it'll be too bad. you should be able to release those wire terminals from their sockets by poking the tangs in just the right spot with a sharp tool.
Finding that was relatively painless.
Repair doesn't look like it'll be too bad. you should be able to release those wire terminals from their sockets by poking the tangs in just the right spot with a sharp tool.
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Ted K (May 29th, 2024)
#26
CF Active Member
Wow! I've been watching this discussion with interest the past few days, and am so glad you found the issue. I hate rats and mice! Squirrels too (had one get in my attic recently). They are so destructive.
You are an amazing neighbor, and God bless you for going above and beyond to help the widow lady in your neighborhood. I know this was a LOT of time and effort on your part to fix her car, and know that she appreciates it.
You are an amazing neighbor, and God bless you for going above and beyond to help the widow lady in your neighborhood. I know this was a LOT of time and effort on your part to fix her car, and know that she appreciates it.
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Ted K (May 30th, 2024)
#27
CF Junior Member
Feel sorry for you! I know that mice can cause a lot of trouble. Besides, the wirings look like a complete mess. You need to get rid of rodents in your house and garage. That's where you start.
Last edited by mountainmanjoe; May 30th, 2024 at 2:08 PM.
#28
Greetings! As noted in the Original Post, the vehicle belongs to a widowed neighbor lady. Her husband will be passed away 2 years this coming Saturday. Consequently neither the vehicle nor the garage with the mice are mine. When her husband was alive I know that he kept the trapline and mouse poison available. Losing a spouse and life long partner changes a lot of things.
#29
Wow! I've been watching this discussion with interest the past few days, and am so glad you found the issue. I hate rats and mice! Squirrels too (had one get in my attic recently). They are so destructive.
You are an amazing neighbor, and God bless you for going above and beyond to help the widow lady in your neighborhood. I know this was a LOT of time and effort on your part to fix her car, and know that she appreciates it.
You are an amazing neighbor, and God bless you for going above and beyond to help the widow lady in your neighborhood. I know this was a LOT of time and effort on your part to fix her car, and know that she appreciates it.
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jfmorris (May 30th, 2024)
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