Fixed the gear change issue sort of but now the transmission has new issues. I took the pan off for an oil & filter change. Oil was a red/brown colour. Bottom of the pan had silvery sludge almost like grease that was gritty in it. Managed to get around 4L of oil out of it. Replaced the oil filter, took 1/2 & 3/4 shift solenoids out tested them for clicking as well as ohms, both were 25ohms and clicked fine. One solenoid did have have its screen partially blocked (one without the spring). Also checked the 3-2 downshift solenoid and the opposite one think it’s called the PWM solenoid and both seemed ok. Also changed the oil in the transfer case while I was there. After the oil change first drive was exciting as it looked as though I had my gears back. Taking off seemed a bit sluggish/ delayed however once going managed to get all gears so it seemed, for a while it was even downshifting manually changing the gears.

Unfortunately that was short lived as the transmission started acting up after a few minutes. Felt as though the gears were slipping or more so it couldn’t at times decide what gear it needed particularly when giving it some extra acceleration to get from 60-80km for eg or to take off from a stop. If I take it really easy it comes good for a bit and then goes bad shortly after. At one stage I went from a stop position to taking and it was again a bit sluggish, put a little extra acceleration down and it just wasn’t going anywhere quicker, next min it’s like it shifted automatically to 1st, started screaming then just got stuck in neutral rolling. I’m at a loss where to go from here, is it possible it’s my torque converter, maybe although the solenoids seemed ok they are stuffed or is my transmission just buggered. There’s more than enough oil in it. Still no codes or engine lights but the stupid ABS failure, traction control & stability service lights are back. Any help appreciated, hopefully some pain killers will at least fix my migraine 🤦‍♀️.

 

I don't remember, so................ how many miles/km????

When was the last time you changed the Trans Fluid & Filter before?

That "sludge" was likely (did it have glitter?) worn out band material and it is time for a rebuild.

 

Thanks Doc for your reply. It’s currently at 196000km. This is the first time I’ve changed the fluid and filter, I purchased the hummer back in 2015 when it originally had 169000km. Over the years I havnt done much driving with it and it’s only done 1 short beach trip and been off-road twice, nothing extreme. I have no idea unfortunately when the transmission was last serviced, looking at the oil I’d say it hasn’t been for a while. The sludge I’m describing reminded me of bearing grease in texture but was silvery in colour, gritty as well. Since yesterday the hummer is pretty much now just stuck in 1st gear, revs up to say 5000-6000 rpm and then just hits neutral and nothing. Prior to the oil change my issue was it was just stuck in 3rd gear and wouldn’t select anything else while driving, after the oil change and cleaning/testing of the solenoids yesterday my gears came back but then the slipping/ over reving and struggling to select gears started pretty quickly and went downhill fast.

 

If you changed only the pan fluid, you still have several liters of old fluid in the system because you are not changing the fluid in the converter.

 

I did think that but I wasn’t sure how else I could get the rest out as I don’t have access to a flush machine. My original plan was if it fixed my issue to drive for a bit and drop the fluid again to hopefully replace most of it. Is there any other way to remove additional fluid?, I did try putting one of those fluid extraction hand pumps down the oil fill tube but it only removed about 2L with the other 2L coming from the pan.

 

Just get a rebuild already.

 

All good sorry for wasting your time.

 

 

Hi all,just had a rebuild on my transmission and now it's not going into over drive. I believe it the TCM issue as previously mentioned. Can any one tell where I can get a new one coded to my vehicle. I have contacted a ebay site in the US but apparently they don't have them. Did anyone have a contact here in Australia that can re code a second hand one?????​​​​​​​help please!!!!!!!

 

You’ll have absolutely no luck finding anyone here in Australia to re code or do anything to the hummers computers or electrical system. I gave up after contacting so many different businesses even ones that solely deal in TCM & Computers, Auto electricians, mechanics, Holden GM no one wanted a bar of it. I have no idea why as the programs for it are easy enough to download of the GM site if you have the right gear to install them. In the end I got mine ordered from a company in the USA that sells you second hand ones and re codes them to suit your car. I think it ended up costing me around $1200 AUD to get the TCM & computer done by them, that included postage. Postage is around $270. The issue after that is you will have an engine light because you will still need someone to re set the crank angle sensor, I can’t even find anyone to do that so I’ll probably just put my old computers back in as that wasn’t my issue anyhow. I ended up finally finding a local transmission shop to rebuild mine for a good price. Even trying to find someone to rebuild the transmission wasn’t easy, and it’s a fairly standard transmission that’s in a lot of Holden’s. But if you have recently just had yours rebuilt I’d be talking to the guys that rebuilt it first as it’s probably not your TCM, could be a solenoid if they didn’t replace them. I replaced all mine myself prior to getting the rebuild done. I also got the shop to upgrade some of the parts including sun gear & valves while there.