Auto transmission issues

[aussie damo]

Gday all,
I drive the truck yesterday for the first time in a few weeks and when I got on freeway, stuck cruise on at 100 kmh (60 odd mile) it would shift between 4 and 3 on the slightest incline. It has never done it before.
I switched off cruise and tried to hold throttle in one spot ant it would still do it?
Any one have any ideas?
Btw 05 QC
Thanks in advance.

 

[oldcolt]

Have you serviced the transmission lately?

 

[rottenronnie]

Gday all,
I drive the truck yesterday for the first time in a few weeks and when I got on freeway, stuck cruise on at 100 kmh (60 odd mile) it would shift between 4 and 3 on the slightest incline. It has never done it before.
I switched off cruise and tried to hold throttle in one spot ant it would still do it?
Any one have any ideas?
Btw 05 QC
Thanks in advance.

Sorry, have to ask...Is it actually shifting from Overdrive (4th) down into 3rd or is the convertor just dropping out of lockup? That would be an approx. 750 r.p.m. increase.
An actual 4th to 3rd shift would cause a much bigger r.p.m. jump than that.

 

[aussie damo]

Sorry, have to ask...Is it actually shifting from Overdrive (4th) down into 3rd or is the convertor just dropping out of lockup? That would be an approx. 750 r.p.m. increase.
An actual 4th to 3rd shift would cause a much bigger r.p.m. jump than that.

This is my first auto ever.
Not sure what the difference is between the two this you described. It was fine today though so I will book in for a trannyservice.

 

[aussie damo]

Have you serviced the transmission lately?

I don't know I will do that first this week.

 

[10-1=9]

Kick down is when you mash the accelerator and the transmission automatically shits to the next lower gear. Like 4th to 3rd gear.

Torque converter lock up is when a clutch inside it applies to stop all internal slippage. Then it acts like a manual transmission with direct drive between the crank shaft & transmission input shaft. Just letting off the accelerator will unlock it so the vehicle can coast. The manufacturers started using them back in the 1980's to improve fuel efficiency.

 

[stealth78]

Kick down is when you mash the accelerator and the transmission automatically shits to the next lower gear. Like 4th to 3rd gear.

Torque converter lock up is when a clutch inside it applies to stop all internal slippage. Then it acts like a manual transmission with direct drive between the crank shaft & transmission input shaft. Just letting off the accelerator will unlock it so the vehicle can coast. The manufacturers started using them back in the 1980's to improve fuel efficiency.

Another reason I like my 6 speed... It has never shit on me.

 

[aussie damo]

I did a code check today
I knew and it came up with p0121 tps sensor
Could that have made the rpm play up?
Does anyone have an oem part number and will see if they have any tps in Australia.

 

[VENOMOUS1 RACING]

I did a code check today
I knew and it came up with p0121 tps sensor
Could that have made the rpm play up?
Does anyone have an oem part number and will see if they have any tps in Australia.

Yes the TPS can affect the trans unlocking TC or downshifting as you said. Pretty common part that any parts store usually has here in US. Hopefully same down
Under

 

[oldcolt]

I did a code check today
I knew and it came up with p0121 tps sensor
Could that have made the rpm play up?
Does anyone have an oem part number and will see if they have any tps in Australia.

I have a new NAPA TPS and a slightly used OEM in my garage. If you can't find one, pm me your address, and I will mail you your choice.