riskset
14th December 2012, 08:29 PM
hi all,
my petrol/lpg 1990 tb42s has lost overdrive. takes gears 1 thru 4 just fine, but will sit in 4th at 90k to 100k without locking up. unfortunately we were on middle section of trip round oz, so have driven home to investigate. i had an AT service completed before we left, and fluids changed and levels checked when the problem first occurred. it was not fluid levels related.
my approach has been to check the electrics via electronic control unit first before pulling anything apart as i have never pulled down an AT unit. also thought the more specific i can be the cheaper it might be. anyway, the only odd readings i am getting are 10v on pin 17 (full throttle switch) when releasing accelerator (shud be 1v or less), 3.35v (should be 3.4 -> 4.4v) on full accelerator - nearly, but is it a meaningful shortfall?, and confirmation via PIN 22 that the lock up solenoid is getting no voltage. in particular, the fluid temp sensor is feeding voltage (although i didn't confirm all ranges).
i talked to wholesale automotive and man were they helpful. basically suggested getting the vehicle to lock up speed, then manually feeding voltage to the solenoid to check this is the only issue, then problem solve why the ECU is not sending voltage originally.
i've read with interest others issues with GQ AT's and just thought i'd contribute.
wasn't sure if this should go in electrical or drivetrain.
will update as i go, and please comment if you have any contributions.
cheers,
my petrol/lpg 1990 tb42s has lost overdrive. takes gears 1 thru 4 just fine, but will sit in 4th at 90k to 100k without locking up. unfortunately we were on middle section of trip round oz, so have driven home to investigate. i had an AT service completed before we left, and fluids changed and levels checked when the problem first occurred. it was not fluid levels related.
my approach has been to check the electrics via electronic control unit first before pulling anything apart as i have never pulled down an AT unit. also thought the more specific i can be the cheaper it might be. anyway, the only odd readings i am getting are 10v on pin 17 (full throttle switch) when releasing accelerator (shud be 1v or less), 3.35v (should be 3.4 -> 4.4v) on full accelerator - nearly, but is it a meaningful shortfall?, and confirmation via PIN 22 that the lock up solenoid is getting no voltage. in particular, the fluid temp sensor is feeding voltage (although i didn't confirm all ranges).
i talked to wholesale automotive and man were they helpful. basically suggested getting the vehicle to lock up speed, then manually feeding voltage to the solenoid to check this is the only issue, then problem solve why the ECU is not sending voltage originally.
i've read with interest others issues with GQ AT's and just thought i'd contribute.
wasn't sure if this should go in electrical or drivetrain.
will update as i go, and please comment if you have any contributions.
cheers,