VT Intermittent Transmission Problem

[squiddley_diddley]

G'day all,
Recently my VT has not being going into top gear.
For the first 20 minutes after starting it will behave normally, going into top gear fine but after a while it gets to around 80 k/p/h and just keeps on plugging away in 3rd.

There's been no slipping, no strange noises, it just refuses to go into top gear.
Costs me a fortune in fuel on long trips, not to mention putting a strain on everything else.

Normally it'll be doing around 1500 - 1600 rpm @ 100 k/p/h but now it it's working harder 2500 - 2600 rpm to get it to sit @ 100 k/p/h.

Any hints before i take it to a transmission place and have to get a second mortgage to pay for an overhaul??

Thanks in advance.

[s_ikari2015]

Speedo gear/pulse generator. I've seen it before where a car will occasionally, but not always, refuse to change gear upwards. It's because of the "pulse generator" as people have described it, it doesn't work properly and so the computer thinks the car isn't actually moving, so there's no need to change gears etc.

It's something that can be fairly cheap to replace, compared to transmissions.

[misha]

Hi
I have the same problem and I took it to Holden in Mandurah where they did the 'computer test' and tell me that it needs a new transmission as it had code 68, though driving it 1st to 3rd are perfect. No surging or lagging in those gears, but won't click into 4th. Do you think their computer can be wrong if it could be a gear/pulse generator? So I am looking at other people first as I thought it would be more like a solenoid. Anyone any ideas??

[HARVZ-6]

Myne does that but 288***ks doesnt help :P

hot days on long trips, lots of hills driving, towing or thrashing make mine refuse to grab 4th and the convertor wont lock up

but if i turn the car off an restart it, problem solved for awhile

i think its a heat cut-out of the convertor lockup from slippage

[grumpyvn]

g'day all,my 99 vt was doing the same thing,3000 rpm at 100 klicks, ignition on then off and you would get another 12-15 mins,i never found what the prob. was cause she ate a piston. this is way off subject but the donk has died now and has been replaced(motor harness box)out of a late2000 mod but it will only run on the orig. computer,if i plug the new one in,it wont crank at all.can anyone help! this is a worry for me cause i have allready blown one engine and i think it might leaned out(i havent opend it up yet but ive got metal in the oil and a crack in the block)and in trip computer hidden features i have no pin code- vin no.-needles dont move and a few other things that is on every other VT ive seen.does anyone else think the car yard has dudded me?

[dazza71]

my vt did the same you could drive around town with no prob but when you got on the highway it would go to 3000rpm and not come down it cost me $1,350 for reco transmisson

[viper2104]

it will only run on the original computer because that's the only one that has been linked to the BCM (body control module) - its a security feature. You can use another computer if you get it linked to the BCM using tech2.

[kart_racer]

g'day all,my 99 vt was doing the same thing,3000 rpm at 100 klicks, ignition on then off and you would get another 12-15 mins,i never found what the prob. was cause she ate a piston. this is way off subject but the donk has died now and has been replaced(motor harness box)out of a late2000 mod but it will only run on the orig. computer,if i plug the new one in,it wont crank at all.can anyone help! this is a worry for me cause i have allready blown one engine and i think it might leaned out(i havent opend it up yet but ive got metal in the oil and a crack in the block)and in trip computer hidden features i have no pin code- vin no.-needles dont move and a few other things that is on every other VT ive seen.does anyone else think the car yard has dudded me?

As above, the car will only run with the original PCM due to VATS system.

Just swap the memcal from the new PCM to your old one. New tune, but your car will detect it's own PCM.

[grumpyvn]

thanks a heap people,i will give it a go

[Krizpy]

My VT has all of the above problems...Thinking i may be able to fix it by replacing the TPS,i changed it out for a new one and now i have no 4rd gear at all.I put the old TPS back in and i still have no 4th gear... i am becoming more convinced that this is an electrical problem that we all share in common. My error code was 85(transmission) while other people are getting 19,68 ,but the oil in the trans is clean and there is no shuttering or grinding. All i can think is i have loosened something when i was changing the TPS,so i am taking is to an auto elec today because i dont think replacing the trans will fix it.Has anyone else solved this(common) problem yet?

[tx4000]

Change PCM, mine was same, replaced PCM all fixed, will need to be linked to BCM via Scantool.

[9C1pack]

tx4000
Change PCM, mine was same, replaced PCM all fixed, will need to be linked to BCM via Scantool.

So by changing the PCM you stopped the 3000 rpm @ 100kph?

I have been having this intermitant problem with my 97 VS for years.
I had a kit put in the trans and a new converter to fix it 3 years ago and the damn thing still does it occassionally. It goes fine around town even on trips out to about 160km. But every now and then it does the 3000+ rpm @ 100kph thing, always on long gradual hills, I notice the revs creep up from 1800to 3000 or higher. I can usually get it to stop by taking my foot off the throttle and reapplying it and it then behaves normally. The trans fluid is dark and smelly after the last slip 2 weeks ago and I will be changing it soon. The engine management light has never lit up and no codes are recorded on the scan tool.
Guy who rebuilt the trans has been very helpful by putting in solenoids, TPS, manifold pressure switch but as it is so damn intermittant, just when I think its fixed and 12 months later it will do it again.
So if I buy a PCM from the wreckers, do I need to get it set up by a scan tool or can I just swap the memcal. Any advice would be appreciatted