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Model specific boards => Golf mk2 => Topic started by: Sgt_Lemon on 02 November 2013, 17:50

Title: Throttle switch test
Post by: Sgt_Lemon on 02 November 2013, 17:50

Car started having really high idle a few days ago and have found that there is no change to idle when the throttle switch is unplugged. I tried a live tester to check the switch but got no live. Is there more tests I should do and where does the other end go so I can check there?

Title: Re: Throttle switch test
Post by: oakgreener on 02 November 2013, 22:24

They go to the ECU

Title: Re: Throttle switch test
Post by: Mr Blue on 03 November 2013, 13:32

Common for the wires to break near the throttle switch.

Plugged in, engine running.

rev the engine just past idle, press the throttle switch - the revs should drop.

The other switch is for wide open throttle if I remember correctly.

No diagram but just beep test the wire to the ecu or Pin 11 according to this

http://www.a2resource.com/electrical/management/digifant2.html

Title: Re: Throttle switch test
Post by: Sgt_Lemon on 04 November 2013, 15:34

Thanks, at the moment I don't have a multimeter so I can't run a circuit test on the wires. However I do have a live tester. At what points should these wires receive a live signal? I found an inline splice further down the connection earlier that looks ok but I want to check the live on ecu side.

Title: Re: Throttle switch test
Post by: oakgreener on 04 November 2013, 20:18

You'd be looking at very small voltages and you won't be able to determine very much without a circuit diagram and an amount of electronics know-how. All you can do is check the continuity of the wires and that the switches are working properly. You can do this with a multimeter set on the ohms scale.

Title: Re: Throttle switch test
Post by: Sgt_Lemon on 07 November 2013, 14:30

Got the Haynes manual out to find the wire locations. Have checked the switch wires back to ecu and there is no break in the circuit. Checked the voltage across the switch and it reads 5v as the manual states. I wanted to remove the throttle body from the inlet to have a look at the switch mounted underneath however the Allen key near bent it half before the first bolt came loose so I would rather not risk trying to get it off. Is there something else which could be the cause of this problem? The car still holds the symptom of high idle and there is zero difference when the throttle switch is unplugged. When the full open throttle switch is pressed by hand the idle drops back down to the recommended range.

Title: Re: Throttle switch test
Post by: weazgti on 08 November 2013, 08:09

Now go pull blue temp sensor plug off. If there's no difference then you want to be looking there

Title: Re: Throttle switch test
Post by: Sgt_Lemon on 29 November 2013, 09:03

Coming back to this again, I dug out my Haynes manual for the wiring diagrams and was able to do a circuit test on all the wires the the throttle switch, they were all good. That suggest to me that its past that switch and must be one of the two mounted on the throttle body. Is there a way to test both the top and bottom one (potentially replace) with the throttle body still on the car. The Allen key bolts look perfectly rounded and I don't want to mess with trying to remove it.

Title: Re: Throttle switch test
Post by: gazareth on 04 December 2013, 20:00

both switches do exactly the same thing. which is why if the idle switch isn't doing its job and you press the wide open throttle switch your car will idle right. with the throttle fully closed you should have continuity at the 2 terminals on plug. and continuity with throttle fully open. with the throttle anywhere between the 2 it should be open circuit. so it defo looks like you have a fault in the switch under the t/b.

Title: Re: Throttle switch test
Post by: Sgt_Lemon on 05 December 2013, 09:06

I thought as much, if I push in the open throttle switch on top the idle calms down, Atm I have the idle screw out to compensate. Can the switch under the t/b be taken out while leaving the t/b on the car?

Title: Re: Throttle switch test
Post by: matt@onlychargeddubs on 05 December 2013, 09:09

The mount the idle switch is fixed to is common for moving on G60 throttles so I'd imagine others are doing the same thing.

One of my first checks is this, it is easier to take the throttle off, loosen the screws and adjust the idle switch so it's just clicking against the cable mech when it's fully closed

Title: Re: Throttle switch test
Post by: gazareth on 05 December 2013, 17:58

if the bolts are rounded try tapping in a torx bit or a 12 point bit (like the 1 for the inner driveshaft bolts). much easier to check/adjust idle switch with t/b off. and you can give it good clean while its off.

Title: Re: Throttle switch test
Post by: Sgt_Lemon on 12 December 2013, 18:49

Any suggestion on where I can buy a new switch when I do get round to getting the old one off?

Title: Re: Throttle switch test
Post by: gazareth on 14 December 2013, 16:23

its unlikely that the switch is bad. it has probably just gone out of adjustment. if you take off the rubber intake pipe you will see 2 small torx screws holding the idle switch to underside of throttle body ( a mirror would be handy to see them clearly) when you find them try loosening them of slightly then pull idle switch out towards drivers side and retighten screws. you might just get enough adjustment to get the switch in contact with the throttle linkage that way.

Title: Re: Throttle switch test
Post by: Sgt_Lemon on 15 December 2013, 20:02

Thanks. Will try that. If it works that's a relief.