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Allison OEM Discuss repairing & maintaining an OEM Allison automatic transmission.

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Old 04-19-2019, 11:36 PM   #1 (permalink)
SpikeDmax
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U2106

Need some help here as I'm stumped.

I'm getting codes PO700 and U2106 (as well as U1024,C0237,C0236, C0269, P1781 but believe those are related to U2106....loss of communication with TCM) I'm consistently getting the U2106, the others only occurred once, maybe twice on the CO236,7 (rear wheel speed missing/erratic).

From what I've read it could be ground wire or bad battery. I've cleaned the drivers side ground wire to frame with wire wheel and reattached. I've replaced both batteries with new. Still getting P0700 & U2106 and going into limp mode.

I'm thinking a bad TCM but before I start Spraying & Praying with parts and replacing the TCM is there a way to narrow it down to that issue and not ECM or FICM or?

Any help greatly appreciated.

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2001 GMC Dmax/Ally 2500HD CC, built Trans @ 160k, injectors @ 109k. 196k. ProFab turbo horn, air box mod, Power sliding rear window, Leer Canopy,
Hot Edge/Attitude & Trippin mount, Rhino lined bed,
Toyo MT 285/75/16, Nicktane filter, Neoprene seat covers, Bilsteins 5100, 2nd owner @85k. 200k Nov. 2015. Do all my own work and looking forward to handing my son the keys soon.
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Old 04-20-2019, 08:08 AM   #2 (permalink)
OkDually
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The P0700 DTC is the TCM requesting a MIL.
You need to find an advanced scanner that can read the stored TCM codes to see what the actual trans code(s) are

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Diamond Eye 4" Turbo Back Exhaust w/2.5" Flo-Pro Crossover
AirDog II DF165 w/ tank sock delete - XDP
TD-Max boost controller - Kennedy Diesel
OPS extension hose - Leroy Diesel
Glow Plug Harness- PT Wiring Solutions
Glowshift Maxtow EGT,Boost, Fuel gauges
Boost & Fuel Pressure Bolts - Leroy Diesel
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Old 04-20-2019, 11:20 AM   #3 (permalink)
SpikeDmax
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Thanks for the reply. Is the code U2106 not the trans code? Will there me more information with an advanced scanner? I'm currently using a Scan Gauge...not sure how advanced that is but will look into getting it scanned by a shop.
Thx
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2001 GMC Dmax/Ally 2500HD CC, built Trans @ 160k, injectors @ 109k. 196k. ProFab turbo horn, air box mod, Power sliding rear window, Leer Canopy,
Hot Edge/Attitude & Trippin mount, Rhino lined bed,
Toyo MT 285/75/16, Nicktane filter, Neoprene seat covers, Bilsteins 5100, 2nd owner @85k. 200k Nov. 2015. Do all my own work and looking forward to handing my son the keys soon.
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Old 04-20-2019, 11:49 AM   #4 (permalink)
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Quote:
Originally Posted by SpikeDmax View Post
Thanks for the reply. Is the code U2106 not the trans code? Will there me more information with an advanced scanner? I'm currently using a Scan Gauge...not sure how advanced that is but will look into getting it scanned by a shop.
Thx
U2106 is a communication code related to communications between the pcm, tcm and ficm.
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1996 K3500 6.5L,( "F" Eng #141 cast block) 5 speed manual, crewcab, dually longbed: 208,000mi.
Diamond Eye 4" Turbo Back Exhaust w/2.5" Flo-Pro Crossover
AirDog II DF165 w/ tank sock delete - XDP
TD-Max boost controller - Kennedy Diesel
OPS extension hose - Leroy Diesel
Glow Plug Harness- PT Wiring Solutions
Glowshift Maxtow EGT,Boost, Fuel gauges
Boost & Fuel Pressure Bolts - Leroy Diesel
2/0 Battery Cable Upgrade - PT Wiring Solutions
PMD w/#9 resistor and Re-Location Kit, mounted to bumper - Leroy Diesel
GM-5 Turbocharger
4.10 gear ratio
OptiLube summer + Formula


Proud member #1039 of The 3500 Dually Club

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Old 04-21-2019, 06:43 AM   #5 (permalink)
Rvn4me
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Quote:
Originally Posted by SpikeDmax View Post
Thanks for the reply. Is the code U2106 not the trans code? Will there me more information with an advanced scanner
P0700 is the TCM requesting a MIL (Malfunction Indicator Light aka: "check engine"). All the 700 code does is tell the ECM "something's wrong" and to illuminate the MIL. There is another code in the TCM that you need to pull that will actually tell you what the malfunction is.
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Old 04-21-2019, 12:41 PM   #6 (permalink)
SpikeDmax
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The other code is U2106

TCM communication failure.

I'm trying to figure out what would cause this. I've regrounded major points of ground and replaced batteries. Have checked wiring to TCM and have found no broken or frayed wires...that were obvious.

My hunch is failed TCM unit but want to eliminate everything else before replacing.

Any help or suggestions appreciated
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2001 GMC Dmax/Ally 2500HD CC, built Trans @ 160k, injectors @ 109k. 196k. ProFab turbo horn, air box mod, Power sliding rear window, Leer Canopy,
Hot Edge/Attitude & Trippin mount, Rhino lined bed,
Toyo MT 285/75/16, Nicktane filter, Neoprene seat covers, Bilsteins 5100, 2nd owner @85k. 200k Nov. 2015. Do all my own work and looking forward to handing my son the keys soon.
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Old 04-28-2019, 11:43 AM   #7 (permalink)
SpikeDmax
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fixed!

Wanted to post an update for anyone doing a search for this code.

I replaced the TCM unit with a rebuilt one I got off eBay. So far so good and all works again.
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2001 GMC Dmax/Ally 2500HD CC, built Trans @ 160k, injectors @ 109k. 196k. ProFab turbo horn, air box mod, Power sliding rear window, Leer Canopy,
Hot Edge/Attitude & Trippin mount, Rhino lined bed,
Toyo MT 285/75/16, Nicktane filter, Neoprene seat covers, Bilsteins 5100, 2nd owner @85k. 200k Nov. 2015. Do all my own work and looking forward to handing my son the keys soon.

Last edited by SpikeDmax; 04-28-2019 at 11:44 AM.
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Old 04-28-2019, 11:47 AM   #8 (permalink)
OkDually
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Quote:
Originally Posted by SpikeDmax View Post
Wanted to post an update for anyone doing a search for this code.

I replaced the TCM unit with a rebuilt one I got off eBay. So far so good and all works again.
Glad you got the issue fixed.
Thanks for giving us an update!

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1996 K3500 6.5L,( "F" Eng #141 cast block) 5 speed manual, crewcab, dually longbed: 208,000mi.
Diamond Eye 4" Turbo Back Exhaust w/2.5" Flo-Pro Crossover
AirDog II DF165 w/ tank sock delete - XDP
TD-Max boost controller - Kennedy Diesel
OPS extension hose - Leroy Diesel
Glow Plug Harness- PT Wiring Solutions
Glowshift Maxtow EGT,Boost, Fuel gauges
Boost & Fuel Pressure Bolts - Leroy Diesel
2/0 Battery Cable Upgrade - PT Wiring Solutions
PMD w/#9 resistor and Re-Location Kit, mounted to bumper - Leroy Diesel
GM-5 Turbocharger
4.10 gear ratio
OptiLube summer + Formula


Proud member #1039 of The 3500 Dually Club

Online   Reply With Quote Quick reply to this message
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