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4 low issues !!

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Old 01-25-2017, 12:16 PM
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Default 4 low issues !!

Ok to start I got 99 blazer with a sas Dana 44 front and 60 rear ....I swapped the 233 autotrac t case to a 231c and now the trans goes crazy when shifting into low ...I've herd that I need to ground a wire on the pcm or something like that ...can't really find anyone that has info on this ...so if anyone can help with this it would be much appreciated thanks
 
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Old 01-25-2017, 12:34 PM
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The wiring diagram I am looking at is for a newer 2nd gen with the 233 and it shows a gray/black wire at the original TCCM location that is the 4LO indicator wire that runs to the PCM. I cannot tell from the wiring diagrams what the TCCM does to this wire to let the PCM know that it is in 4LO though; whether it grounds it or applies voltage and if it applies voltage if it is 5V or 12V.
 
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Old 01-26-2017, 12:19 PM
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Originally Posted by swartlkk View Post
The wiring diagram I am looking at is for a newer 2nd gen with the 233 and it shows a gray/black wire at the original TCCM location that is the 4LO indicator wire that runs to the PCM. I cannot tell from the wiring diagrams what the TCCM does to this wire to let the PCM know that it is in 4LO though; whether it grounds it or applies voltage and if it applies voltage if it is 5V or 12V.
hmm ok that kinda helps me any idea what pin number it is on the tccm?
 
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Old 01-28-2017, 08:18 AM
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According to the wiring diagram in the NV233 No Mode Switch (i.e. 2HI to 4HI) tech article, it is C1 on the TCCM and C4 (connector 4 - black connector body) cavity 23 at the PCM.

Your best bet to determine what the TCCM does on that wire to communicate with the PCM would be to find someone with a working NV233 that you can back-probe the wire at the TCCM to see what happens when you change ranges. I do think that you are right though in that the TCCM grounds this wire.
 
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Old 01-29-2017, 01:50 PM
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Originally Posted by swartlkk View Post
According to the wiring diagram in the NV233 No Mode Switch (i.e. 2HI to 4HI) tech article, it is C1 on the TCCM and C4 (connector 4 - black connector body) cavity 23 at the PCM.

Your best bet to determine what the TCCM does on that wire to communicate with the PCM would be to find someone with a working NV233 that you can back-probe the wire at the TCCM to see what happens when you change ranges. I do think that you are right though in that the TCCM grounds this wire.
I found some diagrams of it and it says it switches from 12 volt to 0 when 4lo is activated so I'm gona try to ground it and see what it does and hope I don't make more problems....thanks for the help
 
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Old 01-29-2017, 01:54 PM
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Please do follow-up with your results!
 
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Old 03-06-2017, 07:14 PM
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so just an update ....i tried to ground said wire going to the pcm and nothing has changed at all..the truck still kinda goes into "limp mode" when the t-case in is 4 low almost like it has no torque at all...sill trying to figure out a way to trick the pcm into knowing its in 4low goin to do more testing tomorow to figure out what the voltage is in it normal start and maybe give it power....any info would be appreciated thanks
 
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