Surging revs

[Clogs]

When I had ETM problems, this fault came up a couple of times. The accelerator pedal has a resistor that sends a signal to the electronic throttle actuator - no steel cables anymore to the throttle/carburettor with electronic throttles.

Firstly get under to have a look to see if there's dirt where the accelerator hinge and spring are. It's a head under the steering wheel job, with the front seat right back. Blow or suck away any dirt, or use a paintbrush. Then clear the code, and see if it comes back. If it does, try some electrical spray. Repeat. If the code remains, a new pedal sensor may be needed. (A Volvo dealer doesn't do faffing about.. replacement parts is all they would do!)

See PDF for bulbs, but to replace them, there is a fairly messy job getting to the instrument panel, and when it is out, change all the bulbs as they're probably all over 20 years old and likely to fail anytime soon. You can get Osram filament bulbs in a pack of 10 on Amazon fairly cheaply. No 9 (for the lights like ignition, warning lights) and no 11 (to light up the panel in the dark,) in the PDF are needed. I wouldn't know if there are LED substitutes as these are small bulbs and LEDs are often bulkier than old filament bulbs

[Luxobarge]

As above, the code is gold dust as it indicates that in fact you've still got a problem with the ETM. You already have a sacer conversion, so either that's gone faulty again or the fault is at the pedal end, as described above. Given that it's free (apart from the pain of having to crawl under the steering column) I'd definitely be doing as suggested.

From all accounts getting the dash top off to get at the instruments isn't a massively hard job, there's a "how to" in the articles section, although I suspect the pictures might be missing now.

[Baffler]

Originally Posted by Dippydog

About 5yrs ago the revs began surging making the car basically undriveable,this was cured by converting the[Magnetti Marelli]throttle body with a Sacer and everything was good...until last Thursday.

Just curious, Dippydog, have you cleaned the throttle body and butterfly valve in those 5 years?

[Dippydog]

No Baffler I hadn't cleaned throttle body/butterfly until this weekend,unfortunately this didn't help and the fault code remains.Looking on the likes of e-bay a new Sacer is just shy of £67 however if the fault is at the pedal sensor/switch e-bay don't seem to list them only the older type that bolt to the throttle body[which of course mine doesn't have].if it is the pedal sensor/switch is that a dealer only part or are they available elsewhere? I'll try the cleaning/spraying of the pedal tomorrow to see if that helps.

[Baffler]

On Clogs' advice remove the pedal and give it thorough cleaning with contact cleaner. I think it's held in with two or three screws and the connection of course.

Might be no harm to remove the battery, whilst doing so, and join the negative lead to the positive lead to speed up the ECU reset...just in case the values have been upset.

If the pedal resistor is duffers this type pedal, I believe, would have been used on both types of diesel and ME7 engines up to '05 so you could look for one from a C70 perhaps.

[SteveSarre]

Hi DippyDog

On manual cars there is a pedal position sensor that sits between the throttle pedal and a mounting bracket. It detects the position of the pedal with a variable resistor (similar to the variable resistors that are used in the original ETMs).

It is mostly off white plastic about the size of a cigar., I think with a socket at each end that locates on a ball.

The resistor film wears out. Guess £65 from Volvo - I haven't needed one for a while - don't know the part number. Easy to fit.

HTH
Steve

[SteveSarre]

Sorry, I was thinking of this

https://www.volvoparts.tmsmotorgroup...sor-1799-p.asp

but maybe that is irrelevant because it is a

Volvo Clutch Pedal Position sensor

not

Volvo Throttle Pedal Position sensor

[Dippydog]

Well rain stopped play today[I'm not grovelling about on the kerb with my head in the footwell while it's wet!]so no pedal sensor cleaning.However I did need to use the car for half hour earlier this evening and the car ran perfectly so perhaps my removing/cleaning/tinkering the throttle body had some effect after all and it needed some time for things to settle/reset after refitting the throttle body.i'm not counting it as a win just yet,but I'd say if the problem returns it points more toward the Sacer going belly up rather than the pedal sensor?

[Baffler]

Fingers crossed 🤞

[Dippydog]

Yes Baffler fingers crossed indeed,time of course will tell.As ever many thanks to all who replied with thoughts advice,it's very much appreciated.