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Old 08-25-2018, 01:08 PM   #1 (permalink)
mikefos
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P0708 - TCM and Internal Mode Switch @ 68K miles

Howdy,

Truck is in signature below, now w/ 68K miles on it. Used mainly for towing a 9500# travel trailer 2 to 3 times a year, one of those trips from Central Texas to Northern New Mexico or Southern Colorado. Otherwise, mostly garaged or around town.

While leaving Red River, New Mexico on our latest trip the truck seemed to be stuck in 3rd gear going up the initial grade to Bobcat Pass. Pulled over and noticed a check engine light. Took off again and limped into Eagle Nest, New Mexico @ 35mph in limp mode. Pulled over in Eagle Nest and truck wouldn't even go into gear. Read a P0708 code w/ my reader. Cleared and tried to go, but wasn't happening. Towed to Taos, truck on back of tow truck, travel trailer hitched behind tow truck. Towed to GM dealer in Taos, which was a joke, so then we had towed to GM dealer in Santa Fe, 70 miles away, ouch. Tech first replaced internal mode switch inside transmission (drain, switch, new filters, refill) to the tune of about $1100. Tested it and threw a TCM code. Replaced TCM to the tune of about another $1100. Add a week of a rental car to the misery. Running fine now on the way home.

I have a real issue w/ this sort of catastrophic failure on a supposedly HD truck that is well maintained and has only 68K miles. I would like to contact somebody at GM who can maybe do something about this or at least take it seriously and look into it. Any recommendations on who to contact at GM? Anybody else have a similar failure as this w/ such low miles?

Thanks,

Mike

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2010 Silverado 2500HD 2WD
Crew Cab, Long Bed
Summit White, Classic Soft Leather
Duramax/Allison
Fumoto Drain Valve
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PCV Re-Route (All Season Diesel kit)
6" Powder-Coated Black Running Boards
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Towing a 2012 Jayco Eagle Super Lite 308RETS w/ a 1400/14K Equal-i-zer hitch
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Old 08-30-2018, 02:25 PM   #2 (permalink)
mikefos
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Nobody else ever had this type of failure w/ such low miles?

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2010 Silverado 2500HD 2WD
Crew Cab, Long Bed
Summit White, Classic Soft Leather
Duramax/Allison
Fumoto Drain Valve
Fuel Filter Access Door
PCV Re-Route (All Season Diesel kit)
6" Powder-Coated Black Running Boards
Duraflaps
Rear Wheel House Liners
AMP BedStep
Towing a 2012 Jayco Eagle Super Lite 308RETS w/ a 1400/14K Equal-i-zer hitch
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Old 09-04-2018, 10:29 AM   #3 (permalink)
G2GBY
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Quote:
Originally Posted by mikefos View Post
Nobody else ever had this type of failure w/ such low miles?
There’s failures like this everyday but mostly under warranty.
Normally shops only charge for the fix not all the niss diognost labor & parts.
Did they refund you $1100 for Tech first replaced internal mode switch inside transmission (drain, switch, new filters, refill) that wasn’t the fix?

Last edited by G2GBY; 09-04-2018 at 10:32 AM.
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Old 09-28-2018, 03:12 PM   #4 (permalink)
Crafty1
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TCM was the problem, why did they charge you for the good IMS that they decided to change but wasn't bad?
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Old 09-28-2018, 03:16 PM   #5 (permalink)
mikefos
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Quote:
Originally Posted by Crafty1 View Post
TCM was the problem, why did they charge you for the good IMS that they decided to change but wasn't bad?

Both were the problem. After initial diagnosis the IMS was determined bad. After IMS replacement another code was thrown during testing and the TCM was determined bad, also, and thus it was then replaced. No problems since (knock on wood), except a few grand poorer. Sort of pissed something like this happened at only 68K miles.
__________________
2010 Silverado 2500HD 2WD
Crew Cab, Long Bed
Summit White, Classic Soft Leather
Duramax/Allison
Fumoto Drain Valve
Fuel Filter Access Door
PCV Re-Route (All Season Diesel kit)
6" Powder-Coated Black Running Boards
Duraflaps
Rear Wheel House Liners
AMP BedStep
Towing a 2012 Jayco Eagle Super Lite 308RETS w/ a 1400/14K Equal-i-zer hitch
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