Odd transfer case shift problem *solved, bad switch*

roadrunner · Post by **roadrunner** » Wed Dec 05, 2007 6:29 pm

I have an 01 Crewcab 4door 4.3 V6 233 new process three button electric shift with an odd shifting problem. It will shift into 4 wheel drive by itself for no apparent reason. It doesn't matter what gear the trans is in or if moving or not. This past winter I had and successfully repaired several problems with the shift system including a front shift indicator switch sticking, a loose actuator bracket, and replaced an encoder motor. This new problem has me stumped at present. The 4hi and 4lo lights will start blinking by themselves and it will shift into 4hi and the lights continue to blink and if in neutral or park or is placed there will shift into 4lo at which time the lights cease blinking and 4lo light comes on steady and is indeed in 4lo. I've tried a different tccm which made no change in symptoms and crawled all over underneath checking wiring and plugins etc to no avail. I also tried unplugging the tccm for a few minutes to clear codes that might be stored in memory with no luck. The only way I can maintain 2wheel drive is to hold the 2hi button and unhook the wires from the back of the three button dash switch. All transmission and engine functions are normal. Just trouble with electric shift. Any suggestions or help would be greatly appreciated. Thanks

Post by **HenryJ** » Wed Dec 05, 2007 6:36 pm

Sounds like TCCM problem to me, unless the switch is stuck.
Of the two the switch is the cheapest to swap. I would probably get a good used one to swap and see if that makes any difference. You have eliminated the encoder with its replacement, so that leaves the TCCM.

roadrunner · Post by **roadrunner** » Thu Dec 06, 2007 3:20 pm

Thanks for the advice HenryJ but I've already secured a good used box #15741322 and tried it to no avail. I've even taken the three button switch apart to inspect for damage or sticking parts to no avail. Only other info I can offer is it seems to bother worse when the weather is damp or humid.

Post by **HenryJ** » Thu Dec 06, 2007 4:34 pm

Tried a good switch yet? Have you been using dielectric silicone on all the connections?

roadrunner · Post by **roadrunner** » Thu Dec 06, 2007 6:44 pm

Odd thing today I was working on the radio. (It has lost the left side speakers) and as I was putting the dash back together I decided to plug in the switches again just for the heck of it. So far is working but has done this before so will wait and see. Yes am using silicone dielectric grease on connectors but no have not tried a different switch yet. Will let you know if problem persists and results when I obtain a different switch if needed.

JaVeRo · Post by **JaVeRo** » Fri Dec 07, 2007 3:57 am

To clear the codes, pull the CTSY LP fuse, (I think it's # 8 ) in the fuse panel by the drivers door. This supplys constant voltage for the memory. Wait a minimum of 60 seconds.

James

roadrunner · Post by **roadrunner** » Fri Dec 07, 2007 12:38 pm

Interesting tip on the fuse thing but I have it on good advice from a GM tech that this might not clear the codes on all models. On mine in particular the power supply for the tccm is routed through the auxillary power supply for the air bag so even removing the battery cables won't clear it. The only effective way I've been able to clear it is by removing rh kick panel and unplugging tccm for a minute or two thus removing all power supply sources from the loop.
Or were you talking about the radio?

Post by **HenryJ** » Fri Dec 07, 2007 12:59 pm

Removing both cables from the battery and waiting for the capacitors to discharge is the safe and easy way. After 3 mintues the SRS capacitors should be discharged. Turn on the ignition with the cables disconnected if you wish. That may or may not help, but it makes me feel better. Then I wait at least three minutes for messing with the SRS.

roadrunner · Post by **roadrunner** » Thu Dec 20, 2007 4:10 pm

Well, here it is two weeks later and the 4x4 electric shift is still behaving itself. Don't know what to say.
Has me scratching my head since I didn't fix anything. Let ya know if it bucks again.

roadrunner · Post by **roadrunner** » Sun Dec 30, 2007 11:28 am

Well, it was too good to last but at least I figured out what's going on.

After having several episodes of shifting on it's own again I replaced the switch on the front diff cable shifter. Close checking with an ohm meter revealed the switch was super-sensitive. Barely moving the switch-ball would produce connection through the switch. The new switch is noticeably less sensitive requiring more movement before connection is established. So far hasn't bothered since.

S-10CREWCAB.NET

Odd transfer case shift problem solved, bad switch

Odd transfer case shift problem solved, bad switch