sensors

[kevo]

Hi all
ive been posting about my woes with my poorly bongo on the lines of dodgy sensors.
I took grahame at works advice and done the diagnostic thing with the wire myself,the fault codes it was showing were 12 and 16, now 12 is the throttle position sensor and i know ive posted about this before,and without wanting to bore everyone to tears does anyone think that this could be the source of my problems, by that i mean the fact that my gears wont change for a good twenty minutes after i have set off, or i have let it run for the same amount of time, after this period it seems to run ok if not a bit sluggish here and there,but
that might be another matter.I hope people are not getting sick of me only posting problems
but being a complete novice you people are the only ones i can turn to.I am very grateful for all your input and hopefully i can get this sorted and post some positive threads.
Thanks,
kev

[mikeonb4c]

Unless the diagnostics advice on here yields any clues, I think you may need to bite the bullet and get a specialist to look at it. Who have we got up that way chums? Or else join the RAC and beak down on the way to Wheelquick in Wigan (mind you is this their area of specialism ). Sorry I can't offer more technical advice and good luck getting it sorted.

[dandywarhol]

You're getting somewhere Kevo - the TPS could cause the gearbox faults you describe. The gearbox relies on the throttle position sensor to tell the gearbox the input line pressure. The 'box changes up when the pressure reading from the governor (driven by the gearbox output shaft) is higher than the line pressure. If the line pressure can't be controlled (like if the TPS was faulty) then it won't change up at the correct time.

Code 16 refers to an Exhaust Gas Recirculation (EGR) fault - this shouldn't affect the gearbox.

Keep at it - I'm, and I'm sure nobody esle, is tired of your posts

[westonwarrior]

If it were mine I would find an auto gearbox specialist (with Bongo knowledge is possible) and let them have a go.

it may be more expensive to begin with but then at least you know it will get sorted with warrenty. anything up to £400

Or you can try and replace the tps and see if that works I think they are about £100+

or again get a complete gearbox and fit that they are available from breakers.

[The Great Pretender]

You're getting somewhere Kevo - the TPS could cause the gearbox faults you describe. The gearbox relies on the throttle position sensor to tell the gearbox the input line pressure. The 'box changes up when the pressure reading from the governor (driven by the gearbox output shaft) is higher than the line pressure. If the line pressure can't be controlled (like if the TPS was faulty) then it won't change up at the correct time.

Code 16 refers to an Exhaust Gas Recirculation (EGR) fault - this shouldn't affect the gearbox.

Keep at it - I'm, and I'm sure nobody esle, is tired of your posts

Help me out here. I know nothing about auto boxes. Can you explain line pressure in relation to the throttle position sensor?

[dandywarhol]

The TPS "tells" the auto box the position of the throttle much the same way a kickdown cable did in carb engined auto setups.

A shuttle valve moves whenever the output shaft pressure (controlled by propshaft speed) is greater than the throttle line pressure (controlled by the TPS) and the moved shuttle valve changes the fluid flow to another clutch set to change up a gear.

So. if you set off with a little throttle open the propshaft line pressure soon overcomes the throttle line pressure and the 'box upshifts. If you set off with the throttle fully open then the propshaft has to turn faster to produce the pressure to overcome the throttle line pressure and the changeup speed is higher.

http://auto.howstuffworks.com/automatic ... ission.htm

[Phill]

If you find the box is knackered let me know as I have one to sell

[mikeonb4c]

The TPS "tells" the auto box the position of the throttle much the same way a kickdown cable did in carb engined auto setups.

A shuttle valve moves whenever the output shaft pressure (controlled by propshaft speed) is greater than the throttle line pressure (controlled by the TPS) and the moved shuttle valve changes the fluid flow to another clutch set to change up a gear.

So. if you set off with a little throttle open the propshaft line pressure soon overcomes the throttle line pressure and the 'box upshifts. If you set off with the throttle fully open then the propshaft has to turn faster to produce the pressure to overcome the throttle line pressure and the changeup speed is higher.

http://auto.howstuffworks.com/automatic ... ission.htm

I've not seen a photo of Dandy, and I'd imagined a suave motorcyclist, clad in leathers and making Ewen McGregor look plain. But it's possible I'm quite, quite wrong here and I'm beginning to wonder...



Forgive me Dandy - couldn't resist

[kevo]

Thanks for replies folks,good explanation by dandy even if i never understood it.
The thing that i dont get is how come it seems to work ok when it is warm, if i was 99% sure
it was the tps i would get a new one but i dont fancy forking out twice.The problem for me
is nobody round here seems to know anything about the bongo which is why i might consider
taking it further afield if i have to. Can anybody reccomend a garage in the north east.
Thanks
kev

[dandywarhol]

The TPS "tells" the auto box the position of the throttle much the same way a kickdown cable did in carb engined auto setups.

A shuttle valve moves whenever the output shaft pressure (controlled by propshaft speed) is greater than the throttle line pressure (controlled by the TPS) and the moved shuttle valve changes the fluid flow to another clutch set to change up a gear.

So. if you set off with a little throttle open the propshaft line pressure soon overcomes the throttle line pressure and the 'box upshifts. If you set off with the throttle fully open then the propshaft has to turn faster to produce the pressure to overcome the throttle line pressure and the changeup speed is higher.

http://auto.howstuffworks.com/automatic ... ission.htm

I've not seen a photo of Dandy, and I'd imagined a suave motorcyclist, clad in leathers and making Ewen McGregor look plain. But it's possible I'm quite, quite wrong here and I'm beginning to wonder...



Forgive me Dandy - couldn't resist

Ewan's aged a bit!

I know a wee bit about cars but no idea why an electric plug has 3 wires

Kev - there's a common link between the TPS, idle switch, coolant temp sender and the ECU.

First thing to check would be the terminal connectors of all these items.

If you PM me your email address I can send you some details on checking the items and the voltages expected at the TPS.

[Grahame at work]

I think Dandy is probably offering the same info I was about to offer regarding the testing of the sensor. This would be taken from the workshop manual - that right Dandy?
I have also been looking at the wiring schematic and there is additional info to be gained from there.

Assuming you can handle the volt meter OK follow what Dandy will give you. But pay perticular attention to the wiring at the connector he will identify - it sits in front of the fuel pump. This is an 8 way connector with seven wires in it. One of the wires is a basic white colour with a black strip running down it and goes into the connector at one corner. The voltage on the wire measured to chassis should be between 4.5 and 5.5 volts, it supplies the 'top end' of the potentiometer with the 'bottom end' of the potentiometer being just about connected to chassis. The wiper is the signal to the ECU for throttle position. This white / black wire ALSO feeds the EGR sensor potentiometer in the same way. SO if you have either a faulty connection along the cable harness (including the connector on the ECU in the passanger foot well) OR a possible fault with the ECU you will get both the EGR and throttle errors as you report - error 12 & 16.
It may be you are not getting a high enough voltage but note that the returns (chassis) connections are also common between the EGR and throttle sensors so look for anything 'odd' looking along there as well (the harness goes around the back of the engine and down the side of the passenger foot well).

Good luck

Grahame

PS I just thought - if you disconnect the EGR sensor (which is at the back of the engine and the connector may be 'hidden' under the mass of stuff there) it will check to see if that is faulty and pulling the voltage down for the throttle position sensor.

[kevo]

THANKS AGAIN GRAHAME,
i will have a look at what dandy has to say and keep you posted.

[mikeonb4c]

I think Dandy is probably offering the same info I was about to offer regarding the testing of the sensor. This would be taken from the workshop manual - that right Dandy?
I have also been looking at the wiring schematic and there is additional info to be gained from there.

Assuming you can handle the volt meter OK follow what Dandy will give you. But pay perticular attention to the wiring at the connector he will identify - it sits in front of the fuel pump. This is an 8 way connector with seven wires in it. One of the wires is a basic white colour with a black strip running down it and goes into the connector at one corner. The voltage on the wire measured to chassis should be between 4.5 and 5.5 volts, it supplies the 'top end' of the potentiometer with the 'bottom end' of the potentiometer being just about connected to chassis. The wiper is the signal to the ECU for throttle position. This white / black wire ALSO feeds the EGR sensor potentiometer in the same way. SO if you have either a faulty connection along the cable harness (including the connector on the ECU in the passanger foot well) OR a possible fault with the ECU you will get both the EGR and throttle errors as you report - error 12 & 16.
It may be you are not getting a high enough voltage but note that the returns (chassis) connections are also common between the EGR and throttle sensors so look for anything 'odd' looking along there as well (the harness goes around the back of the engine and down the side of the passenger foot well).

Good luck

Grahame

PS I just thought - if you disconnect the EGR sensor (which is at the back of the engine and the connector may be 'hidden' under the mass of stuff there) it will check to see if that is faulty and pulling the voltage down for the throttle position sensor.

Cripes



Sorry, must stop butting in and butt out instead

[Aethelric]

Thanks for replies folks,good explanation by dandy even if i never understood it.
The thing that i dont get is how come it seems to work ok when it is warm, if i was 99% sure
it was the tps i would get a new one but i dont fancy forking out twice.The problem for me
is nobody round here seems to know anything about the bongo which is why i might consider
taking it further afield if i have to. Can anybody reccomend a garage in the north east.
Thanks
kev

I got my bongo from vgsimports in Sunderland http://www.vgsimports.co.uk/ Vince is a great guy, and may be able to help.

Dave

[lizard]

No keep posting, it's the only way to get the problem solved. Hammer that keyboard.

I know a wee bit about cars but no idea why an electric plug has 3 wires

These plugs have three wires in case two of them break, then you will still have a spare.