AF20 Auto box problems

[dave's.veccy]

I know a lot about engines but sod all on auto boxes

My Vectra B has a AF20 box fitted, which the Cavalier also uses so i can ask this here

The problem im having is that some mornings, it takes ages to engage first gear and secondly, when its cold the auto box behaves. As soon as it warms up, its rough engaging gear and its constantly going into limp home mode until its cool to which the process starts all over again.

The oil has been changed recently and is to the correct level using the correct checking technique

I know it needs a tech 2 to check it but im not being ripped off by a dealer nor a private garage, the last one i went to said if they found a fault, it will be £40. I know theres a flaming fault so why should i have to pay for it

[v6sri]

If it rev's alot before it bites as if the clutch was slippin you have stretched bands which menas its knackered mate or did you mean its hard via the selector,or it could be 101 other things there is just no tellin this is just in my experience of them. Whenever there is a problem with an auto box just give up they're too expensive to fix either get a new one or make it manual which is what i did

[dave's.veccy]

It weird tbh, when you pull away, it can just sit there and not creap when you release the brake but then all of a sudden, bang it goes into gear yet other times its good as gold and other times, you can be sitting at the lights with foot brake operated, it goes into neutral electronically like it should then after about a minute or so, sometimes it will just jolt into gear

Ive done a stall test on it and it revs at just over 2K rpm but i dont know what Vauxhall's stall test allowances are (this tests the brake bands etc if you didnt know)

[Cavalier342]

My guess buddy would be an electronic fault, or the selector cable is loose. have you tried the famous "paper-clip" trick to diagnose the fault/s youself?

[dave's.veccy]

Ive tried the paperclip test but because ive the computer on the dash, thats where it tells me i have a fault and not the usual flashing S so a fault code can be flashed up

Ive done a bit of research through google and from what im reading, its not terminal and as you say, something electrical but just what i dont know

Next on the menu is to remove the selector and clean it out then refit and try it

[Cavalier342]

oh rite ok. umm ye i suppose that wouldnt hurt to try well make sure it isnt somethin stupidly simple as it was with my Cav...months of working on and waiting for the selector switch to start working after replacing it, and all it was was a blown fuse so ye make sure it aint a simple thing cos that would be frustrating lol

[dave's.veccy]

ive been through the fuse box and all seems ok

I did notice this evening though, the selector on this is quite sloppy so im going to remove it and clean it out. Once ive done that ill readjust the cable just to make sure

[Cavalier342]

yep that sounds like a good plan mate. oh by the way i wired in 2 more white LED's into the reverse lights and its bright lol looks amazing at night though from the driver's seat when i'm reversing with the brakes applied, the whole rear windscreen and the interior trim is lit up red and white and if u stand behind the car.... bright

[dave's.veccy]

yep that sounds like a good plan mate. oh by the way i wired in 2 more white LED's into the reverse lights and its bright lol looks amazing at night though from the driver's seat when i'm reversing with the brakes applied, the whole rear windscreen and the interior trim is lit up red and white and if u stand behind the car.... bright

Right, ive cleaned the selector switch out which sorted it.....until it got upto 90 degrees on the coolant temp gauge to which it started all the same again

Im so close to throwing the autobox away

[Cavalier342]

ok thats strange. i really dont know what the problem is could be some kind of wire issue, maybe something shorting out or loose somewhere, i really dont know. i suggest just trying to find out more info about it to be honest, but i wouldnt say its worth chucking away, because it might just turn out to be simple

[dave's.veccy]

I was driving around town today and whilst waiting at lights, traffic etc i stuck it in neutral myself and noticed the temperature stayed down and it was smooth going into gear. Once the temp got up slightly it was julting into gear again which was at the level crossing at the top of my road so drove it home. I think its something temp sensor related, maybe going out of range or something but im just guessing. I really dont want to swap the box to manual

[andyc]

good chance its 2/3 shift solinoid. My Cav's got the same problem when its cold it works ok the the EML comes on. Shifts ok manually.

Valve is about £150.00 and its a bit of an arse to fit

Cheers
Andy

[Envoy CDX]

Get another selector switch / whatever it is and whack that on, should be the same for prefacelift Omegas and Cavaliers - easiest possible solution first?

[Cavalier342]

easier said than done buddy i couldnt find a selector switch for my Cav for ages. but i just kept trying by leaving online request forms on different websites and eventually got there Car Quip UK was where i got mine from, if it helps at all

[dave's.veccy]

All im finding is empty bays in Cavalier and Vectra Auto's, The engine in the boot and the box gone. I looked at a few Astra ones today and can definately say they are different. I think the selector and valve gear on the Omega is different too.

Andy, could you give me a little more info on the symptoms with your box so i can compare please bud??

The box shifts perfectly when in fault mode ive noticed although im controlling it

I did notice it done the wierd thing with the first gear selection when it wasnt quite warmed up which is a first so whatever it is, its dying. It brought up the old thing on the MID 'Automatic Transmission' about 5 seconds after doing it and just putting itself in third which isnt good news trying to pull away quickly

[Cavalier342]

sure mate. well basically, when i bought the car, the guy told me....i quote "you have to warm it up in the morning when its cold for a few mins otherwise u'll be burning fuel" lol ok no u dont.. i thought. anyway, basically right after i got it, i found what i thought was the potential reason for a quick sale when the engine's cold, when i started it, as soon as i selected down the panel...P - R - N - D, that damn "s" light started flashing on the dash panel, and if i tried pulling away, it just went at a snail's pace, which i soon found out later to be in 3rd gear lol. anyway, it also for some reason started making a funny wining noise, as like a wrecked gearbox, or some sort of mechanical robot type noise, which i found lol. but basically, when it warmed up, as the engine temp. gauge needle got out of the blue "cold" area, it worked fine. then after some time, it just packed in for good until i got it replaced. so basically it was playing up when it was cold at first, fine when it warmed up, then gave in altogether. the hardest part i found though is finding a new one..... i wouldnt even go for a dealer...my quote for a new switch was £275 so ye...best trying car breakers and scrapyards really. hope this helps mate

[Envoy CDX]

there's an Calibra Auto in my local breakers- who's got a picture of what I'm looking for,

[dave's.veccy]

Hmmm, mine happens the other way round, when warm it plays up, it hates going from neutral (which the box has selected) to first which, not all of the time the message comes up. Ive driven it around this afternoon and its been fine. Bloody thing!

The selector has been cleaned out and all looks ok inside, no wear inside at all

Gary, could do with some non porous speed sensors, one is towards the back of the gearbox near the engine, the other is located by the chassis leg, possibly under the battery on a Calibra. I dont want to pay £25 each for them so the cheaper the better, or as they are small enough,*cough* in the pocket. Wipe them on a seat before doing that though

[dave's.veccy]

Ive managed to get my hands on a well known repair manual (not a Haynes either) so ill be having the auto box in bits tomorrow, i now know where the solinoid valves are

[Cavalier342]

cool nice one good luck with it buddy

[Envoy CDX]

Gary, could do with some non porous speed sensors, one is towards the back of the gearbox near the engine, the other is located by the chassis leg, possibly under the battery on a Calibra. I dont want to pay £25 each for them so the cheaper the better, or as they are small enough,*cough* in the pocket. Wipe them on a seat before doing that though

How very dare you.... assuming I would do such a thing....

















Aye, not a problem - get a picture pointing out said bits and I'll see about whipping them out

[dave's.veccy]

ill get some pics if i have a spare 5 mins with no rain about

[dave's.veccy]

Here is something weird, the other day i noticed my battery light wasnt coming on when the ignition was on. Ive checked all the wiring and noticed a new alternator. Ive changed the bulb (no idea how long this has been dead, the bulb was black, possibly from over voltage some time in the past) and this is the weird, or good bit

It occasionally does the thing with first gear but its doing it less often now and the thing with neutral has gone. The temperature is staying down too

Ive probably spoken too soon but im hoping its fixed itself due to having incorrect voltage possibly because the battery not being charged properly

[dave's.veccy]

Gary, could do with some non porous speed sensors, one is towards the back of the gearbox near the engine, the other is located by the chassis leg, possibly under the battery on a Calibra. I dont want to pay £25 each for them so the cheaper the better, or as they are small enough,*cough* in the pocket. Wipe them on a seat before doing that though

How very dare you.... assuming I would do such a thing....

















Aye, not a problem - get a picture pointing out said bits and I'll see about whipping them out

I dont encourage it at all

[kingofthekerb]

I've got similar problems with mine.

I've had the selector changed, i've cleaned the selector switch and had a new cable fitted.

My oil is well crappy though, just don't know how to do a FULL change yet. Got a fair idea just getting the finer details sorted.

Have you flashed the codes out for it?? You have to short out different pins where the plug goes for the auto codes.

Automatic gearbox. Short pins A and C on the diag plug

17 Solenoid 1-2/3-4 (Voltage Low)
21 Throttle Position Sensor (Voltage High)
22 Throttle Position Sensor (Voltage Low)
23 Coolant Temperature Switch (Voltage High)
25 Solenoid 1-2/3-4 (Voltage High)
26 Solenoid 2-3 (Voltage Low)
27 Connection Solenoid 2-3/Solenoid TCC
28 Solenoid 2-3 (Voltage High)
29 TCC Solenoid (Voltage Low)
31 No Engine RPM Signal
32 Pressure Regulator Solenoid (Voltage Low)
33 Pressure Regulator Solenoid (Current High)
36 TCC Solenoid (Voltage High)
38 No Transmission Input RPM Signal
39 No Transmission Output RPM Signal
41 Gear Error Hydraulic Fault (usually an internal transmission mechanical failure - forward clutch ?)
42 Pressure Regulator Solenoid (Short Circuit)
47 Down Shift Protection
48 Battery (Voltage Low)
49 Battery (Voltage High)
56 Selector Switch (Incorrect Signal)
65 AT Oil Temperature Sensor (Voltage High)
66 AT Oil Temperature Sensor (Voltage Low/High)
67 AT Oil Temperature Sensor (Voltage High)
75 Transmission Switch (Voltage Low)
76 Engine TPS Load (Signal Incorrect)
77 Kickdown Switch (Voltage Low)
78 AT Shift Time (Too Long)