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TPS test measurement advice please
Posted: Sat Jun 14, 2014 3:52 pm
by The Wanderer
Hi there. I recently had the diesel fuel pump refurbished and since refitting, I've had the HOLD light flashing. The TPS was changed for a secondhand one which reportedly was working fine, but the flashing HOLD light is still there and a test on the ECU gives code 12, which points to a faulty TPS. I've had a good read around the forum threads and fact sheets but can't figure out the best way to test if the TPS is functioning correctly. I understand that the readings for closed and open are approx. 1.3v and 4.2v but can't figure out where to attach my test meter to check the readings, and whether I can test the TPS whilst the vehicle is stationery. Can anyone advise how to go about this please?
The most similar thread to my problem appears to be this one
http://www.igmaynard.co.uk/bongo/forum/ ... t=test+tps, where M Bongo solves the problem by adjusting the TPS position, which I have tried but makes no difference. There is also a thread here
http://www.igmaynard.co.uk/bongo/forum/ ... 87#p139787 where Corblimey describes how to test the TPS, but I can't figure out where pin 21 is on my ECU. Is he describing a different ECU? Mine's below the glove box to the left hand side of the passenger footwell in a '95 2.5 diesel.
Thanks

Re: TPS test measurement advice please
Posted: Sat Jun 14, 2014 4:21 pm
by g8dhe
Does he not mean 2I pin;

Re: TPS test measurement advice please
Posted: Sat Jun 14, 2014 5:20 pm
by The Wanderer
Thanks Geoff, but how does that diagram translate to my ECU please?
Re: TPS test measurement advice please
Posted: Sat Jun 14, 2014 5:35 pm
by g8dhe
The ECU is the box in the middle as the 3 in the letters in the middle indicate

The bits around it are all the various sensors etc.
Re: TPS test measurement advice please
Posted: Sat Jun 14, 2014 6:15 pm
by The Wanderer
I think I see where you mean. The box that says B2-01 ECU(E) that has 3 sets of rectangular blocks in? So which pin? Third pin bottom left of middle block as mentioned in Corblimey's post is 2L, but I thought he said 2l, which looks like it's 4th pin top row of the middle block. But actually, my ECU doesn't look like this. It looks like an upside down version of the one shown in the Diagnostic fact sheet I think.
Re: TPS test measurement advice please
Posted: Sat Jun 14, 2014 7:50 pm
by The Wanderer
Here's what my ECU looks like

Re: TPS test measurement advice please
Posted: Sat Jun 14, 2014 9:53 pm
by g8dhe
No that is the OBD socket, the ECU is to the right mounted on the firebreak directly in front of the passengers feet,it has 3 separate plugs hence the numbering of the pins on the ECU, each plug is shown with colour codes below the diagram.
Here is a picture of the ECU on a V6 very similar;

Re: TPS test measurement advice please
Posted: Sun Jun 15, 2014 1:36 pm
by The Wanderer
Aha, thanks, that makes sense now! The OBD is what I used when I got fault code 12 on dash. Do I need to do test with ECU whilst driving, as suggested by Corblimey, or can the vehicle be stationery?
Re: TPS test measurement advice please
Posted: Sun Jun 15, 2014 1:40 pm
by g8dhe
I think you will be find its fine stationery, as its looking at the revs rather than the roadspeed, that only comes into play with the ECU-AT section.
Re: TPS test measurement advice please
Posted: Sun Jun 15, 2014 1:52 pm
by The Wanderer
That's great. I couldn't really work out why it would be necessary to drive to test it.
Thanks for your help,
Geoff
Re: TPS test measurement advice please
Posted: Wed Jul 09, 2014 12:48 pm
by The Wanderer
Just to complete this thread, I thought I would post what the solution to this issue turned out to be. Rather than the TPS itself, there is a post coming up from the fuel pump that the TPS mounts onto. The post rotates to give the TPS throttle position info and is adjustable. When my pump was reassembled, the post had not been set exactly in the right position, so was sending the wrong voltage to the TPS which in turn was sending incorrect info to the gearbox. The auto gearbox specialist I ended up going to tested the voltage with a meter and then adjusted the post until correct. Problem solved! I gave them the correct approx. measurements as seen in other posts - 1.3v closed, 4.2v open.