tccm problem
- Thread starter sylvain N
- Start date
Molson02536
New member
hi nmy question is where is the fuse for tccm on a jimmy 2001 i cant find it
There are a couple of fuses you will want to check. They are located in the under hood fuse box. The TBC ( truck body controller) and ATC (automatic transfer case) fuses. Start with that amd keep me posted, the other common issues with the TCCM is cossosion. The wire harness that connect to the TCCM corrode and there is no votage going in to the TCCM, you TCCM is located located behind the kick panel on the passengers side.
http://kylestubbins.com/files/images/03_blazer_tccm_01b.jpg
i check that tommorrow and is weird before my 4x4 stop working when i push the swicth panel i hear a sound like electric shock from behind the glove boon tccm locatio they do that every time i engage the 4x4 but now nothing work even the yellow ligth on the panel everything dead idont have computer to read code on pin13
idont have computer to read code on pin13Molson02536
New member
i check that tommorrow and is weird before my 4x4 stop working when i push the swicth panel i hear a sound like electric shock from behind the glove boon tccm locatio they do that every time i engage the 4x4 but now nothing work even the yellow ligth on the panel everything dead
You don't need a reader to get the tccm code. TCCM codes are, 1, 2, 3, 4
Pin 13 is the pin use use to ground to check codes.
If you did indeed ground #13 the 4wd light will blink
Code "1" is "RAM standby power" and is considered normal, may be caused by clearing the codes.
Code "2" is "Encoder fault"
Code "3" is "TCCM motor circuit"
Code "4" is "RAM/ROM failure"
Ground pin 13 at the data connector under the dash. The lights on the switch should flash. You are only going to have a choice of 4 codes as mentioned above. Here is the procedure to further clarify.
Diagnostic Trouble Code (DTC) Displaying:
The transfer case shift control module is equipped with the ability to store diagnostic information, which is useful to a technician in the event of module, component or wiring failures. This information can be retrieved from the transfer case shift control module by way of flash codes, which are displayed on the three transfer case shift control switch buttons. These buttons are located on the instrument panel to the right of the steering wheel Before obtaining DTCs, perform the following transfer case control module (TCCM) Self-Test.
TCCM Self-Test
Observe the transfer case shift control switch indicators while turning the ignition switch to RUN. A properly operating system will flash all indicators and then will return to the current gear. If the system is operating normally, then proceed to Displaying Codes.
If the TCCM failed the Self-Test, then test the following circuits.
• Battery Positive Voltage, and Ignition Voltage for battery voltage
• Ground Circuit for ground
• Diagnostic enable circuit for an open or high resistance
• Transfer case shift control switch connector
If the above circuits are normal but the TCCM still fails the Self-Test, replace the TCCM.
DTC Displaying
Turn OFF the ignition for 10 seconds.
Connect PIN 13 on the data link cable (DLC) to a ground. The DLC is located in the cab under the instrument panel on the driver's side.
Turn ON the ignition, with the engine OFF.
Observe the transfer case shift control switch select buttons for flashing codes. Refer to Diagnostic Trouble Code (DTC) List above.
Important: If the transfer case shift control switch buttons all blink only once and then stop, no fault codes are stored in the transfer case shift control module.
• When one DTC is stored in memory, that code will blink that number of times followed by a 3 second pause and then repeat.
• If more than one code is stored, the first code will blink, followed by a 3 second pause and then the second code will blink.
• This sequence will continue until PIN 13 on the DLC is no longer grounded.
• If the TCCM will not communicate the presence or absence of DTCs, test the above circuits in Self-Test Step 2. If the circuits are complete, then replace the TCCM.
Here is a break down of your 4WD system:
1) let's start off with the easy things -- have you checked your fuses? Don't assume that just because the fuses are labeled 4WD that they are the only ones for your 4WD system! Fuse 10 (on the Jimmy/Blazer) is for the courtesy lights but guess what? It also controls the logic side of the TCCM (+5VDC). Pin 6 (thinner orange wire) should produce +5VDC and should be HOT AT ALL TIMES (meaning you should be able to read +5VDC on the line anytime, key on or off). The two large orange wires are your +12VDC lines and are controlled from the 10A fuse located in spot #15.
Check your LARGE orange wires as you are getting +5VDC logic as the lights are coming on on the dash. The +12VDC is used for the encoder motor, check to make sure you have +12VDC at both the large orange wires (they are right beside each other, and there are two large black wires beside them that are ground).
Notes: All black wires are ground -- all orange wires are power (hot). There is a 10A fuse (#15) for the 4WD system, located in the fuse panel. There is a 20A fuse, located under the hood, that is also for the 4WD system (I'll have to look up the fuse number). The 4WD system also pulls from the 10A courtesy lamp fuse (#10).
2) The vacuum switch (located on the firewall http://www.kylestubbins.com/files/blazer_vacuum_switch.jpg) or vacuum diaphram (located under the battery) could be malfunctioning. The job of these components is to pull on a cable which engages the front, right 4WD hub. I don't think this is likely to be your problem as you should probably hear the encoder motor running (changing the drive mode from 2Hi to 4Hi/4Lo) but there is a sensor on the hub to tell the TCCM when it is engaged, so it could be problem.
3) the encoder motor/module is bad. This is the module/motor that is mounted directly to the transfer case, who's job it is to physically move the gears of the transfer case to put the TC into the various modes (2Hi, 4Hi, 4Lo). You also want to check the wires at the encoder motor as they are exposed to the elements and could be damaged by something flying up under your vehicle (not likely, but possible).
4) The TCCM (located under the passengers kick panel) has wires that are corroded / broken. Poor connections anywhere along the route will cause problems and most times intermittently, which are a real PITA to find. The TCCM could be bad as well. If I had to guess either your encoder motor is shot, or bad wires on the TCCM.
If you're really into it, I'll post the schematics for the wiring of the system -- this will allow you to trace and test points along the system to pinpoint the problem. I hope I have given you some direction to be able to start troubleshooting your 4WD system.
Here is a picture of your wire harness to your TCCM that you need to inspect for corrosion and damaged wires. http://kylestubbins.com/files/images/03_blazer_tccm_01d.jpg
http://www.kylestubbins.com/files/front_axle_switch_&_pcm.jpg
http://www.kylestubbins.com/files/TC_encoder_motor.jpg
http://www.kylestubbins.com/files/TC_shift_control_switch.jpg
http://www.kylestubbins.com/files/TCCM_power&ground.jpg
Molson02536
New member
Take your time and start with the simple like always and check your 4WD selection button. Remove the switch panel from the dash, just pops out and test the wire leads to the switch. Did the TCCM Self test performed without any issues as noted.
( TCCM Self-Test: Observe the transfer case shift control switch indicators while turning the ignition switch to RUN. A properly operating system will flash all indicators and then will return to the current gear. If the system is operating normally, then proceed to Displaying Codes. )
Once again take your time and keep me posted, be glad to help you save some money and get your 4WD system working again soon.
ok molson today i try this from my 4WD selection button unplug and test wire the plug
wit 2 wire got power in it both wire and the bleu pug got only one wire work
so i dont no if my swicth work drove to my brother he have a blazer with the same 4WD selection button test mine panel on his truck and suprise every thig work and work with is 4x4
so my question is my tccm it is burn ?
wit 2 wire got power in it both wire and the bleu pug got only one wire work
so i dont no if my swicth work drove to my brother he have a blazer with the same 4WD selection button test mine panel on his truck and suprise every thig work and work with is 4x4
so my question is my tccm it is burn ?
Molson02536
New member
It's looking that way
, but before you go and replace the TCCM (find one on Ebay or the Salvage yard) recheck your wire harness and test the TCCM wire harness connector for damages due to corrosion. Once everything has been checked, to lead you that your TCCM is faulty and will need to be replaced. Here are the color code to the TCCM connector.
http://kylestubbins.com/files/images/03_blazer_tccm_01d.jpg
1.Gary/black - PCM 4WD low signal
2. XXX
3.DK Grn/ wh - 4 low switch signal
4.Dk Grn/ wh - 2 Hi switch signal
5.Gray/black - 4 Hi switch signal
6. Orange (small) - Battery positive voltage
7. XXX
8. Brown - front axle switch
9. black/wh - encode signal Ground
10. Black - Ground
11. Lt Grn/Blk - 2 Hi Indicator light
12. tan/Blk - 4 Hi Indicator light
13. XXX
14. Purple/ wh - 4 Low Indicator light
15. XXX
16. Black - Ground
17. Purple - Crank Voltage (hot in start)
18. Orange/ Large - power at under hood fuse block
19. Orange/ Large - Hot at all times
20. Bkack - Ground
21. Black - Ground
22. XXX
23. XXX
24. XXX
25. Dk Grn/ Wh - Instrument cluster ??? VVS signal
26. Yellow/Blk - Encoder channel B
27. Dk Blue/ Wh - Encoder channel A
28. red / Wh - Encoder channel C
29. Brown/ Wh - Encoder channel D
30. Orange - Data Link Connector ( diagnostic enable)
31. Lt Grn/Blk - Automatic shift lock switch supply voltage
32. Red - Motor control B
Gray/black - 4 Hi switch signal
Got a question??..... Just bought a 2000 GMC Jimmy SLT a couple months ago. 4x4 dont work. guy replaced the TCCM and still nothing. Started pulling it apart this weekend and found out big harness that goes to the TCCM he rewired. all colors match, going to check if it's pinned right tomorrow, there's 2 black/white wires, one was not connected with the other. found out the transfer case is engaged, the shaft moves when the truck does.. The indicator lights don't even light up to show it's in 2hi. Can that switch be bad? pushing any of the buttons don't do anything.
any suggestions?
thanks..
any suggestions?
thanks..
couple quiestions?
Just bought a 2000 Jimmy SLT... has the 4 button switch panel. no lights show which drive its in (2hi, 4hi, 4lo, auto 4hi) all fuses are good. The guy that had it before me replaced the TCCM. still nothing. the transfer case is locked in place, the shaft moves when the vehicle does, but 4x4 is not engaged.
Any suggestions?
Just bought a 2000 Jimmy SLT... has the 4 button switch panel. no lights show which drive its in (2hi, 4hi, 4lo, auto 4hi) all fuses are good. The guy that had it before me replaced the TCCM. still nothing. the transfer case is locked in place, the shaft moves when the vehicle does, but 4x4 is not engaged.
Any suggestions?
Just bought a 2000 JImmy SLT couple months ago, 4x4 don't work. the guy that owned it before me replaced the TCCM and still dont work, he unplugged it and gave up on trying to fix it. i want it fixed. when i plugged it in and press any of the 4 buttons nothing happens. no lights flash on it when i turn on the car light stated above they should. fuses are good.
any suggestions?
used to own a 97 S-10 and did more than enough work on that. had the 4x4 go and it was the vacuum actuator. dont seem that way on this.
thanks for any help.
any suggestions?
used to own a 97 S-10 and did more than enough work on that. had the 4x4 go and it was the vacuum actuator. dont seem that way on this.
thanks for any help.
Last edited:
Molson02536
New member
Inspect your 4wd switch at the pins, there common to burnout there. If there is signs of damage, you can take the switch apart and re-solder any connections that look like they have gone bad at the terminals. At worst, visit a Salvage Yard and pick one up for about $5.00 from a Salvaged Jimmy of the same year.
Good luck and keep us posted.
Inspect your 4wd switch at the pins, there common to burnout there. If there is signs of damage, you can take the switch apart and re-solder any connections that look like they have gone bad at the terminals. At worst, visit a Salvage Yard and pick one up for about $5.00 from a Salvaged Jimmy of the same year.
Good luck and keep us posted.
Thanks... Just bought this thing in Sept. 4x4 hasn't worked for a while, the guy tried replacing the TCCM and that wasn't it so he gave up. I want it working so i'm going to do what i can. Had a 97 S-10 so i'm pretty familair with working on this engine and what not..
Will check that out and see what i come up with and keep you posted.. thanks again!
Inspect your 4wd switch at the pins, there common to burnout there. If there is signs of damage, you can take the switch apart and re-solder any connections that look like they have gone bad at the terminals. At worst, visit a Salvage Yard and pick one up for about $5.00 from a Salvaged Jimmy of the same year.
Good luck and keep us posted.
Thanks! will keep you posted on progress. guy before replaced the TCCM so i'm hoping it's this, he never got it working again.
Inspect your 4wd switch at the pins, there common to burnout there. If there is signs of damage, you can take the switch apart and re-solder any connections that look like they have gone bad at the terminals. At worst, visit a Salvage Yard and pick one up for about $5.00 from a Salvaged Jimmy of the same year.
Good luck and keep us posted.
thanks will keep you posted.