2001 Tahoe Transfer Case Issues: C0308 & C0327
July 10th, 2012, 8:51 PM
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2001 Tahoe Transfer Case Issues: C0308 & C0327
Hey everyone, I'm new to these message boards and I just want to start out by thanking anyone & everyone who takes the time to help me out with this issue that I'm currently having with my vehicle. Here's some background information:
Vehicle information:
2001 Chevy Tahoe
5.3L V8 Motor (8th VIN Code: T)
246-NP8 Transfer Case
Codes present:
C0308-Motor A/B Circuit Low
C0327-Encoder Circuit
Parts already replaced:
Transfer Case Selector Switch (New)
Transfer Case Encoder Motor Assembly (Used)
The story:
I acquired this Tahoe with the "Service 4WD" message on the dashboard. There was also no lights lit up on the Transfer Case Selector Switch in the dashboard. I've successfully replaced a Transfer Case Selector Switch on a 2002 Tahoe with a B2725 code in it. I wish (and still hope) that this repair were that simple. I got cocky and didn't scan the vehicle before I bought & installed a new Selector Switch. That was a dumb move. I probably should know better.
Scanning the vehicle with a Snap-On Solus scanner, I get two transfer case codes: C0308-Motor A/B Circuit Low & C0327-Encoder Circuit. Upon clearing the codes, C0308 immediately pops back up into "Current Codes" with the C0327 returning a few seconds later. Once I start the vehicle up, the Transfer Case Selector Switch lights up all 4 buttons for a fraction of a second before going completely blank. There is absolutely no response when any of the buttons are pushed. I get the EXACT same pattern (Lights flash on for fraction of a second, all lights go out, no response) of misbehavior from both the new & the original Selector Switch. This annoying activity will repeat itself every time the ignition in turned on.
After unsuccessfully trying the new Transfer Case Selector Switch, I tried replacing the entire Encoder Motor Assembly with a used, reportedly "tested" Encoder Motor Assembly. No good. Same deal with the Selector Switch & same codes pop back up immediately after clearing them. I'm not 100% sure if my Encoder Motor has an Encoder Ring Switch (Part# 88962315) or not. I haven't contemplated opening the Encoder Motor until tonight. I didn't really think both Encoder Motors would give the same exact symptoms & codes, but they do.
After replacing the Selector Switch & Encoder Motor Assembly, I tried the easier things such as cleaning all of the connector plugs, removing & cleaning G110 on the driver's side frame rail, and checking for constant power at the Selector Switch, Encoder Motor Assembly, & the Transfer Case Control Module. All the plugs are clean. The grounds are cleaned & secured (G110 is the only one I really cleaned). I have constant power to all three. Still no lights on the Selector Switch. Still have two pesky codes (C0308 & C0327).
I thought about ordering another Transfer Case Control Module until I read TSB 05-04-21-002 from March 10, 2005 that says not to replace the TCCM unless I am getting "No communication to the TCCM" (which perfectly communicates those two pesky codes under "Current Codes"), or DTC C0550 (NOT present in my vehicle). It also goes on to say that dealers were replacing the TCCM when 75% of the time the TCCM was NOT the original problem. I can read the data parameters on the scanner fine & I can communicate with it just fine. The odd thing about scanning the vehicle is under "Data" in the TCCM. Every "Encoder Channel (A, B, C, & P)" is "OFF" and "Encoder Gear" says "INVALID". Also, when I try various "Functional Tests" such as commanding the Selector Switch light's ON\OFF, or even turning the "4X4 Service Light" ON\OFF doesn't turn off.
I've also chased wires all day long to check for breakage, melting, cracking, etc. but I can't find or see anything wrong. After replacing the Selector Switch & Encoder Motor Assembly, I've been wondering about grounds & wire continuity. It has my head spinning. I hate electrical diagrams.
The Bottom Line:
Am I missing something obvious here? Electronics is not my strong suit, but I'm thinking I may have acquired an electronic nightmare here. I suppose I'll take apart the original Encoder Motor that I have to check if it has the Encoder Ring Switch tomorrow morning. If it has one, I'll order one new from a dealership. Are there any other grounds besides G110 that I should check? I have tools, access to a lift, scanner, All-Data, and a teeny-bit of mechanical ability. I almost refuse to take a vehicle not under manufacturer's warranty to any dealership, but I might not have a choice on this one. Can anyone help me or attempt to point me in the right direction? Again, thank you in advance to anyone who can help me out. This thing is kicking my butt.
*** SOLUTION *** As described below in my post below, replacing the TCCM (Transfer Case Control Module) cleared my issues up completely. The TSB was throwing me off completely.
Vehicle information:
2001 Chevy Tahoe
5.3L V8 Motor (8th VIN Code: T)
246-NP8 Transfer Case
Codes present:
C0308-Motor A/B Circuit Low
C0327-Encoder Circuit
Parts already replaced:
Transfer Case Selector Switch (New)
Transfer Case Encoder Motor Assembly (Used)
The story:
I acquired this Tahoe with the "Service 4WD" message on the dashboard. There was also no lights lit up on the Transfer Case Selector Switch in the dashboard. I've successfully replaced a Transfer Case Selector Switch on a 2002 Tahoe with a B2725 code in it. I wish (and still hope) that this repair were that simple. I got cocky and didn't scan the vehicle before I bought & installed a new Selector Switch. That was a dumb move. I probably should know better.
Scanning the vehicle with a Snap-On Solus scanner, I get two transfer case codes: C0308-Motor A/B Circuit Low & C0327-Encoder Circuit. Upon clearing the codes, C0308 immediately pops back up into "Current Codes" with the C0327 returning a few seconds later. Once I start the vehicle up, the Transfer Case Selector Switch lights up all 4 buttons for a fraction of a second before going completely blank. There is absolutely no response when any of the buttons are pushed. I get the EXACT same pattern (Lights flash on for fraction of a second, all lights go out, no response) of misbehavior from both the new & the original Selector Switch. This annoying activity will repeat itself every time the ignition in turned on.
After unsuccessfully trying the new Transfer Case Selector Switch, I tried replacing the entire Encoder Motor Assembly with a used, reportedly "tested" Encoder Motor Assembly. No good. Same deal with the Selector Switch & same codes pop back up immediately after clearing them. I'm not 100% sure if my Encoder Motor has an Encoder Ring Switch (Part# 88962315) or not. I haven't contemplated opening the Encoder Motor until tonight. I didn't really think both Encoder Motors would give the same exact symptoms & codes, but they do.
After replacing the Selector Switch & Encoder Motor Assembly, I tried the easier things such as cleaning all of the connector plugs, removing & cleaning G110 on the driver's side frame rail, and checking for constant power at the Selector Switch, Encoder Motor Assembly, & the Transfer Case Control Module. All the plugs are clean. The grounds are cleaned & secured (G110 is the only one I really cleaned). I have constant power to all three. Still no lights on the Selector Switch. Still have two pesky codes (C0308 & C0327).
I thought about ordering another Transfer Case Control Module until I read TSB 05-04-21-002 from March 10, 2005 that says not to replace the TCCM unless I am getting "No communication to the TCCM" (which perfectly communicates those two pesky codes under "Current Codes"), or DTC C0550 (NOT present in my vehicle). It also goes on to say that dealers were replacing the TCCM when 75% of the time the TCCM was NOT the original problem. I can read the data parameters on the scanner fine & I can communicate with it just fine. The odd thing about scanning the vehicle is under "Data" in the TCCM. Every "Encoder Channel (A, B, C, & P)" is "OFF" and "Encoder Gear" says "INVALID". Also, when I try various "Functional Tests" such as commanding the Selector Switch light's ON\OFF, or even turning the "4X4 Service Light" ON\OFF doesn't turn off.
I've also chased wires all day long to check for breakage, melting, cracking, etc. but I can't find or see anything wrong. After replacing the Selector Switch & Encoder Motor Assembly, I've been wondering about grounds & wire continuity. It has my head spinning. I hate electrical diagrams.
The Bottom Line:
Am I missing something obvious here? Electronics is not my strong suit, but I'm thinking I may have acquired an electronic nightmare here. I suppose I'll take apart the original Encoder Motor that I have to check if it has the Encoder Ring Switch tomorrow morning. If it has one, I'll order one new from a dealership. Are there any other grounds besides G110 that I should check? I have tools, access to a lift, scanner, All-Data, and a teeny-bit of mechanical ability. I almost refuse to take a vehicle not under manufacturer's warranty to any dealership, but I might not have a choice on this one. Can anyone help me or attempt to point me in the right direction? Again, thank you in advance to anyone who can help me out. This thing is kicking my butt.
*** SOLUTION *** As described below in my post below, replacing the TCCM (Transfer Case Control Module) cleared my issues up completely. The TSB was throwing me off completely.
Last edited by theKingDP; March 12th, 2013 at 11:14 PM.
March 12th, 2013, 11:00 PM
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Sorry that I did not post an update on this matter. The solution for me was to replace the TCCM (Transfer Case Control Module). I was able to find a guy from a local parts yard that would let me return it if the module did not fix my problem. Unfortunately, it's apparently very hard to find someone that is willing to offer ANY refund on a "used" computer module.
I drove myself crazy, and spent countless hours of troubleshooting this issue. The TSB about the TCCM that GM put out really threw me off. If it wasn't for that TSB, I probably would have suspected a bad TCCM before I ran myself in circles.
I do not know if replacing the TCCM will help any of you guys, but it solved my problems immediately. No updates, no dealership flashing, completely "plug-and-play". I believe I spent $150 on the used module, but like I said before, the gentleman who sold it to me offered to refund if it did fix my problem.
I drove myself crazy, and spent countless hours of troubleshooting this issue. The TSB about the TCCM that GM put out really threw me off. If it wasn't for that TSB, I probably would have suspected a bad TCCM before I ran myself in circles.
I do not know if replacing the TCCM will help any of you guys, but it solved my problems immediately. No updates, no dealership flashing, completely "plug-and-play". I believe I spent $150 on the used module, but like I said before, the gentleman who sold it to me offered to refund if it did fix my problem.
December 12th, 2014, 8:52 PM
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chevy Silverado same problem
I went threw same thing and finally tccm fixed my problem , but less then a month later it fried again burnt same piece on curcuit board twice within a month. This is now becoming a really big problem I don't know whare to start. Any help will b greatly appreciated
August 20th, 2023, 10:15 AM
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I am having trouble with fuse blowing in my 2001 Silverado 1500 with 300000 miles on it, in 4 wheel circuit ever since I had the front axle actuator., and encoder, TCCM and the transfer switch in dash, all replaced at dealership and now it blows fuse when I change position from 4 wheel to 2 wheel drive. it is a 20 amp fuse. after 5 fuses being blown I tried a 25 amp fuse and so far it is fine. Will that 25 amp fuse hurt anything
August 20th, 2023, 2:32 PM
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@trojannnhorse
please don't hijack other people's questions. You need to post a new topic in the Silverado section. Thanks very much.
please don't hijack other people's questions. You need to post a new topic in the Silverado section. Thanks very much.
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March 1st, 2012 10:33 PM
