Transmission shifting weird issue....

SunlitComet · Feb 4, 2011

Remove or Disconnect

Negative battery cable.
Disable SIR.
Retainer from brake pedal pin. Use snap ring pliers.
Switch by unsnapping from pushrod.
Electrical connector from switch.

Install or Connect

Electrical connector into switch.
Switch by snapping it onto pushrod.
Retainer onto brake pedal pin. Use 11mm (7/16 inch) socket to push new clip on pin.
Negative battery cable.
Enable SIR.

Bowie · Feb 4, 2011

What switch is the SIR switch, there seems to be a lot of wires down there? Is ther anything I can take out so I have some more room in there?

Thanks

raptorforme93 · Feb 4, 2011

destroyer1362 said:
If your truck's temp is lower that a certain degree (I don't know what exactly) the computer won't let the tc lock up. If your thermostat is stuck open your truck could be running too cool and that could be the cause for your problem. So watch your coolant temp and see if you need a new thermostat.

Is this why my hoe never shifts at 50 mph when I have just started it on a cold day? I get up to 55 or 60 mph and it doesnt shift until the truck has warmed up to normal temperatures. I figured that it was something like what you said but I was never really sure or cared much to ask since it always shifted once it was warm.

SunlitComet · Feb 4, 2011

Bowie: with key out of ignition lock pull your airbag fuse. #8 I think. Then disconnect the only the yellow colored connectors under neath the dash. At least one but maybe two if your have passenger air bag. Proceed with repair. Reverse the procedure to re-enable SIR system.

Don't want you to get hit by a false airbag deployment.

---------- Post added at 04:51 PM ---------- Previous post was at 04:47 PM ----------

Raptor, iirc the temperature can kill off the overdrive gear as commanded by the PCM. You should be just fine. It is SOP in the PCM. Good enough or should I find some details for you if possible?

EastTXYukon · Feb 4, 2011

Wow! Learning a lot today. My truck does the same thing as Raptorforme93's. I thought it was a problem, but just one I had to deal with on a 15 year old truck with 150k on the transmission. I had no idea that the tranny not shifting into overdrive until it was warmed up was the correct way for it to operate

Thanks for the info Sunlitcomet :beer:

Bowie · Feb 8, 2011

sunlitcomet
I wanted to say thanks for all the help. I could not have done it without you. It has been running great so far, hopefully it keeps up.

The one question I have is: Did I do any damage to the Torque Converter. The tranny had been shifting like that for 5 years or more.

Thanks again

raptorforme93 · Feb 8, 2011

sunlitcomet said:
Bowie: with key out of ignition lock pull your airbag fuse. #8 I think. Then disconnect the only the yellow colored connectors under neath the dash. At least one but maybe two if your have passenger air bag. Proceed with repair. Reverse the procedure to re-enable SIR system.

Don't want you to get hit by a false airbag deployment.

---------- Post added at 04:51 PM ---------- Previous post was at 04:47 PM ----------

Raptor, iirc the temperature can kill off the overdrive gear as commanded by the PCM. You should be just fine. It is SOP in the PCM. Good enough or should I find some details for you if possible?

No youre good man

Thank you though! I figured that it probably wasnt a big deal since everything drobe normal and it did it consistently until the weather warmed up. Thanks!

SunlitComet · Feb 9, 2011

Bowie said:
sunlitcomet
I wanted to say thanks for all the help. I could not have done it without you. It has been running great so far, hopefully it keeps up.

The one question I have is: Did I do any damage to the Torque Converter. The tranny had been shifting like that for 5 years or more.

Thanks again

Ouch. Maybe some extra wear and tear on its clutch. five years is a long time. If you do get a code for a or notice slipping tranny you will know where it is slipping. Just run it till it breaks.

crxx · Mar 29, 2012

had the same problem and such an easy fix! Amazing how a lil $10 switch could handle so much. And thought i was gonna need a new tranny....smh

insadj05 · Jul 19, 2013

Additional questions

Sunlit,
I was driving home today with the 99 tahoe and the rpm's were drifting between 2100 and 1900 like above. However when I pulled off the interstate for the 14 mile back woods trip to the house every I stopped and started I would get hard shifts. Would this switch be causing this also?
Thanks

Transmission shifting weird issue....

SunlitComet

OBS Jedi-Do Good

Bowie

TYF Newbie

raptorforme93

Full Access Member

SunlitComet

OBS Jedi-Do Good

EastTXYukon

Full Access Member

Bowie

TYF Newbie

raptorforme93

Full Access Member

SunlitComet

OBS Jedi-Do Good

crxx

TYF Newbie

insadj05

Member

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