GQ TD42 Auto Conveter lock up at 60kph

[Killametre]

Hi guys my GQ slush box feels as though the lock up converter cuts in around 60kp/h. Under light throtle at 60kp/h the revs go from 1400 to 1200 but it seems to cut in and out a bit as throtle position changes its a bit anoying. I have read that it is not supposed to cut in till around 80kp/h I have not owned the car long and am going out on the hyway to see what happens at higher speeds.
Oil level and colour is good speedo in dash works fine and there are no other problems with shifts etc that i am aware of. Any ideas????
Cheers Andrew

[Bigrig]

Don't know a lot about them other than what I have sussed out lately for mine - could the previous owner have put in a 'low stall' speed converter to ease fuel consumption?? Have a look at the specs on Wholesale Automatics website (Melbourne based) for their low stall converter and it sorta sounds like what you got?

Give Rodney there a call as he knows his stuff and should at least be able to point you in the right direction.

Good luck with it mate and no doubt others may have ideas also.

[Killametre]

A litttle more to add on the open road it shifts up through the gears ok settles in to 4th and then lock up while sitting on 100 if you plant your foot it comes out of lock up but wont kick down to 3rd which makes accel very steady if you push the OD off button she goes back to 3rd and your away. (it will only kick back to 3rd below 90) The shift points in the manual on the forum are for a TB42 not sure if there is much difference but in any case full throttle at 100 should see you back in 3rd. Spoke to wholesale autos in melb they suggestes adj the throttle pos switch up a bit it was .4v to 3.4 adj up to .6v idle and 3.7v wot checked idle,wot and kickdown switches while i was going all ok. Roadtest still the same. Another thing I noticed is that if you take any gear up to say 30000rpm and back off there is engine braking but in 3rd the tacho drops to about 800rpm then blips up to 1400 then back down and just continues to do this as you slow down

I think it may be terminal???

[Killametre]

Done about 2000km since last post gearbox still the same has not got any worse so maybe thats how it will stay, I swaped ecu with one from an old petrol and the converter lockup problem went aeay but 3rd gear eng brake is still same

[NissanGQ4.2]

Done about 2000km since last post gearbox still the same has not got any worse so maybe thats how it will stay, I swaped ecu with one from an old petrol and the converter lockup problem went aeay but 3rd gear eng brake is still same

maybe your TPS is faulty, Scottie ( Bigrig ), has been having trouble with his Auto Box and I believe his TPS was faulty.

[Killametre]

Could be, I have tested it with a multimeter and it checks out ok but the bloke at the local auto shop recons its best to test them with an osiloscope, I am a bit reluctant to shell out any $$ for a new one at this point as the 3rd gear thing has me wondering?? then again i most likely have more than one problem

[taslucas]

Hi mate just found your thread. Ive had/having a lot of trouble with my TB42 Auto box too; tps was actually missing from mine! It changed gears similar to yours. Having been driven so long (before i owned it) without a tps, the torque converter was fried. Been in and out of the workshop for a while.

Also: I think you should be driving with the OD button off unless coasting on the highway. I only have a POWER on/off switch but my mates has the OD button. He drives with OD off 3/4 of the time. But i think 60kph lockout is a bit low

I have a haynes book and it tells you how to do the auto box's self-diagnosis. Handy if you can get hold of one.

Goodluck mate

[NissanGQ4.2]

Hi mate just found your thread. Ive had/having a lot of trouble with my TB42 Auto box too; tps was actually missing from mine! It changed gears similar to yours. Having been driven so long (before i owned it) without a tps, the torque converter was fried. Been in and out of the workshop for a while.

Also: I think you should be driving with the OD button off unless coasting on the highway. I only have a POWER on/off switch but my mates has the OD button. He drives with OD off 3/4 of the time. But i think 60kph lockout is a bit low

I have a haynes book and it tells you how to do the auto box's self-diagnosis. Handy if you can get hold of one.

Goodluck mate

I use my OD button all the time with no problems

[Killametre]

Hi mate just found your thread. Ive had/having a lot of trouble with my TB42 Auto box too; tps was actually missing from mine! It changed gears similar to yours. Having been driven so long (before i owned it) without a tps, the torque converter was fried. Been in and out of the workshop for a while.

Also: I think you should be driving with the OD button off unless coasting on the highway. I only have a POWER on/off switch but my mates has the OD button. He drives with OD off 3/4 of the time. But i think 60kph lockout is a bit low

I have a haynes book and it tells you how to do the auto box's self-diagnosis. Handy if you can get hold of one.

Goodluck mate

Thanks, Yeah the TPS was on top of my hit list along with the revolution sensor but as they test ok at the TCU I am not keen to spend the $$ with the prospect it may not fix it I will keep my eye out for a second hand one to try. If they were faulty when tested I would have no issue replacing them but it is not the case. There is no reason to drive with the OD off(3rd) around town the transmission is built to handle it if they didnt want you to use top at low speeds they would change the shift point in the TCU?

Thanks again for the feedback

[gq4200]

If the converter locks at 60km/h you would know it as you would barely be able to cruise. I used to have a switch in mine to lock as required. If you locked it at 60 you could just 'cruise', the engine revs were that low it was not useable. It may be just going into 4th. Don't forget the lock-up is like a fifth gear, not part of the 4-speed gbox.