Auto won't change up past 3/4 gear

[frinkemon]

Hiya,

I have a diesel auto Bongo which recently no longer gets above about 3rd/4th gear. I'm going 60 and engine is at about 2100RPM, won't go much above 60 without getting to 3K+ RPM!

Sometimes it gets into an odd state where it won't get above about 40MPH, sounds like 2nd gear.

I changed the ATF when this started, and it seems to be at the right level (maybe a little high actually). I thought the ATF chance and subsequent correct level would fix this, but no..

Anybody got any ideas as to what may be happening?

Thanks,
Leigh

[Ian]

Problems with the Auto box are usually accompanied by a flashing "hold" light on the dash. The sequence indicates the precise nature of the issue. But sometimes the hold light itself will not work correctly. What happens if you start the engine and then press the hold button on the gear shift? Does the hold light show on the dash display?

[Northern Bongolow]

a quick check on the wires that go into the side of the gearbox may help, sometimes water in the plugs may affect the voltages seen at the box, give em a clean and a wiggle, costs nowt.

[frinkemon]

The hold light seems fine when I press the hold button.. But I've never seen it light up any other time.

Now I did hear something about a diagnostic interface? That sounds handy!

[Alacrity]

The HOLD light will only flash if there is an electrical problem, as I have stated numerous times on here before, it will not pick up on mechanical/hydraulic faults. If you have a fault with a gearbox operation changing the oil will not 'heal it up' any more than changing the engine oil will cure an engine miss-fire.

What has to be established is if the transmission is being commanded by the computer to change up to 4th (or whatever) gear & the gearbox isn't responding or if the gearbox is just doing as it is told by the computer. In the former instance the gearbox is at fault, in the latter the fault is on the vehicle not within the gearbox.

I doubt looking for fault code will be of any help as the HOLD light isn't flashing.

[mikeonb4c]

I'd get it to a gearbox specialist as unless you feel up to tackling gearbox related stuff that's where you're going to end up anyway. If you're lucky enough to be near Geoff/Alacrity, that's where I'd take it. For as much as i can tell, it sounds more command/computer/sensor related than mechanical. I seem to recall the throttle position sensor being a relatively inexpensive fix if the incorrect commanding is due to a faulty TPS. Hopefully Geoff might comment on that.

[cushers]

My 2.5 TD sits at 50 mph @ 2000 rpm in 4th. I only have 4 gears. There is a post somewhere that shows the speeds and corresponding rpm readings.

Graeme

[teenmal]

Gear Ratios
(mph/2000rpm) for each
gear.
1st – 11.2MPH
2nd – 20.4MPH
3rd – 32.0MPH
4th – 50.3MPH

[Alacrity]

Could be a faulty TPS as Mike says but they normally set a code. If it was out of adjustment it could make it late but but I wouldn't have thought it would stop it changing into 4th.

[frinkemon]

Right well I got a weird fault code from the ATX computer, I shorted the input pin and the HOLD light flashed like this:

LONG flash 6 short flashes 9 short flashes

(Cant remember if I said that already?)

Anyway, this does not seem to relate to any fault code I can find..

So I replaced the TPS anyway, took it for a spin and...traffic and more traffic..

So since the issue really starts at about 60MPH (it won't go above 60) I'll have to wait till tomorrow for a proper run. However, I did test the old and new TPS, the potentiometer is about 4.4K, I get 40 Ohms at lowest reading and 4.4K at the highest, same on both. There is another little black box on a connector on the TPS wiring loom, no idea what that does.

Anyway, Ill take her for a spin tomorrow and see what happens.

Failing that, I wondered if it could be a solenoid issue. So I'll test them as well if I can find a wiring pinout, else I'll drop the bottom off again, water some more transmission fluid and test..

Thanks all for the help so far. I'm in West London, so if anybody knows a good gearbox place let me know, may need them!

--
Leigh

[mikeonb4c]

Right well I got a weird fault code from the ATX computer, I shorted the input pin and the HOLD light flashed like this:

LONG flash 6 short flashes 9 short flashes

(Cant remember if I said that already?)

Anyway, this does not seem to relate to any fault code I can find..

So I replaced the TPS anyway, took it for a spin and...traffic and more traffic..

So since the issue really starts at about 60MPH (it won't go above 60) I'll have to wait till tomorrow for a proper run. However, I did test the old and new TPS, the potentiometer is about 4.4K, I get 40 Ohms at lowest reading and 4.4K at the highest, same on both. There is another little black box on a connector on the TPS wiring loom, no idea what that does.

Anyway, Ill take her for a spin tomorrow and see what happens.

Failing that, I wondered if it could be a solenoid issue. So I'll test them as well if I can find a wiring pinout, else I'll drop the bottom off again, water some more transmission fluid and test..

Thanks all for the help so far. I'm in West London, so if anybody knows a good gearbox place let me know, may need them!

--
Leigh

Sounds to me like your approaching things in the right order. A pity Alacrity is so far off as he's the obvious choice. Mind you, he might know of someone near you.

[frinkemon]

What are Alacritys contact details please? I mean, it could turn into a couple of days away with the kids

[g8dhe]

The wiring is shown here plug B2-12;

[mikeonb4c]

What are Alacritys contact details please? I mean, it could turn into a couple of days away with the kids

I believe he's in Eastbourne and a search of old threads suggests he's here:

http://www.autogearboxes.co.uk

...And ask for Geoff who has a Bongo. Or you could send him a PM.

Good luck, keep us posted.