mystery switch reflash

[SRehberg]

I posted awhile back about the issues with installing a Mystery Switch, so I asked about adding an electronic controller. Well, not the type that gives up easily, I reinstalled the mystery switch with again problems. It worked just fine for about 3-4 shift cycles, then for some odd reason the trans wouldn't unlock even with the switch in the "forced unlock" (i. e. open switch position). Needless to say, I shuddered to a stop (torque converter seemed to slip a little?) killed the engine then restarted it. Now I was stuck in 2nd gear, no others would work. I took it home and removed all the stuff again, so my question is: evidently the PCM needs a reflash; can it be done BEFORE installation of the mystery switch? I ask this because if something screws up, I have to drive out of town to a dealer and in 2nd gear with 4. 10 rear, that could take awhile! I can't see where an electronic controller would act any different, it just helps to prevent forgetting to disengage the torque converter lockup.



Any ideas why the torque converter would lock up and stay that way even with the forced unlock position? Sorry for the questions, this seemed so straight forward, but it sure is hard on the truck.

 

[Joe G.]

Steve,



That locked up in spite of everthing symptom is exactly the symptom reported in the TDR mag by one of the first people to try a mystery switch on a '96. I think you should get it reflashed before doing anything else.

 

[tp0d]

Have you tried disconnecting the batteries to kill any memory in the PCM? I`d do that first... I have a 96 also... was thinking about the mystery switch, but I guess I`ll wait heh...



good luck



-jerry

 

[SRehberg]

I tried leaving the batteries disconnected for about 2hrs then reconnected them. That's the only way I got the truck to behave normally again after removing the switch wiring. I'll call the dealer and see when and if he can reflash the PCM... do I just ask for the latest update or anything specific?

 

[SRehberg]

Well, I made an appointment with the dealer in the next town, but I am not real confident as to what will happen. He asked me why I wanted the reflash, and what symptoms the truck was displaying that I seemed to think needed attention. I explained what was going on and he said he has to have the truck to plug into, to see if it needs updating. Is there a particular update I should ask for? He wants $60 to check it, so I don't want him to tell me "sorry, your PCM is just fine, and we don't see any error codes. " Any suggestions? Thanks again for the help.