4 button 4X4 switch lights don't work, TCCM does not click
#11
11-03-2013, 02:09 AM
You may need to eject the individual connectors one at a time from the plastic harness plug to clean and inspect the crimp onto the wire. I feel for ya, working "under the dash" with short wires can be a real pain.... good luck......
#12
09-15-2016, 09:37 PM
Replaced TCCM
I want to throw this out there, since I couldn't find this solution in the forum and others may have a similar problem:
My 1999 GMC Jimmy (Blazer) 4x4 auto selector switch would only light up for a second when the switch was selected to "ON". The OBD-II scanner at Oreilly said there was Error code P0740 "Transfer case circuit fault". Checked the switch and the circuit was fine. Checked the wires to the encoder motor, were a bit old but seemed okay. Opened the Transfer Case Control Module (TCCM), put my finger on one of two relays to determine which was making the "click click, click click, click-click" sound every time I turned the ignition switch to "on". If I turned the switch to ignition very quickly, the switch lights would all stay lit.
For years the Jimmy has been making clicking noises like I have the turn signal on, and I think those noises were coming from a faulty relay in the TCCM. I found that TE Connectivity sells a compatible relay for the Siemens T72MD121-12, their product is
1461067-1, however it requires an order quantity of 1000! So I bought a remanufactured TCCM from Oreilly for $180. Put it in and 4x4 works properly. My problem solved! I'd like to also note one of the signal wires was loose, that may have caused the premature failure of the relay.
My 1999 GMC Jimmy (Blazer) 4x4 auto selector switch would only light up for a second when the switch was selected to "ON". The OBD-II scanner at Oreilly said there was Error code P0740 "Transfer case circuit fault". Checked the switch and the circuit was fine. Checked the wires to the encoder motor, were a bit old but seemed okay. Opened the Transfer Case Control Module (TCCM), put my finger on one of two relays to determine which was making the "click click, click click, click-click" sound every time I turned the ignition switch to "on". If I turned the switch to ignition very quickly, the switch lights would all stay lit.
For years the Jimmy has been making clicking noises like I have the turn signal on, and I think those noises were coming from a faulty relay in the TCCM. I found that TE Connectivity sells a compatible relay for the Siemens T72MD121-12, their product is
1461067-1, however it requires an order quantity of 1000! So I bought a remanufactured TCCM from Oreilly for $180. Put it in and 4x4 works properly. My problem solved! I'd like to also note one of the signal wires was loose, that may have caused the premature failure of the relay.
#13
09-19-2016, 11:07 AM
I have a 2000 GMC Jimmy with the 236 transfer case and the 4 button 4X4 switch on the dash.
So let’s start from the beginning; a while back the 4X4 switch lights were acting strange…blinking when going into 4hi and then going back into 2hi, but after pushing the button a couple of times it would work fine and go into 4hi. Then it stopped working and would only go into 2hi or 4low.
Back then I took out the Battery and checked the Vacuum Actuator and Cable for the Front Differential, and after finding a vacuum line that was off to the vacuum solenoid on the firewall everything was fine again.
Then a couple of weeks ago I decided to do annual maintenance and change the transfer case fluid. Afterwards I went on a short road trip to get the new fluid worked into the various gears and when I put it into 4low it would not come out, and the lights on the dash went out for the 4X4 switch.
Since then I have replaced the 4X4 Dash switch, the Transfer Case Encoder Motor (the transfer case is now back in 2 hi) and the Transfer Case Control Module but the lights are still not working on the 4X4 Dash switch.
My question is; does something need to be reset in order for the lights to come back to the dash switch? Even when I turn the key over to start the truck, the lights do not blink.
Any advice is appreciated.
Thanks,
John
So let’s start from the beginning; a while back the 4X4 switch lights were acting strange…blinking when going into 4hi and then going back into 2hi, but after pushing the button a couple of times it would work fine and go into 4hi. Then it stopped working and would only go into 2hi or 4low.
Back then I took out the Battery and checked the Vacuum Actuator and Cable for the Front Differential, and after finding a vacuum line that was off to the vacuum solenoid on the firewall everything was fine again.
Then a couple of weeks ago I decided to do annual maintenance and change the transfer case fluid. Afterwards I went on a short road trip to get the new fluid worked into the various gears and when I put it into 4low it would not come out, and the lights on the dash went out for the 4X4 switch.
Since then I have replaced the 4X4 Dash switch, the Transfer Case Encoder Motor (the transfer case is now back in 2 hi) and the Transfer Case Control Module but the lights are still not working on the 4X4 Dash switch.
My question is; does something need to be reset in order for the lights to come back to the dash switch? Even when I turn the key over to start the truck, the lights do not blink.
Any advice is appreciated.
Thanks,
John
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