signals to TPS help please

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carl4x4
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Joined: Thu Mar 14, 2019 6:38 pm

signals to TPS help please

Postby carl4x4 » Thu Mar 14, 2019 6:52 pm

Hi, I have just installed an ME221 into my 1991 Mx5 as part of a 1.8 mk2 (1999 non-vvt) engine transplant. The car is running now (of sorts) but the ECU seems to be not picking up the mk2 variable TPS. If I use the configuration tool and push the throttle down then no voltage changes are recorded.

I have checked the wiring and wired it like this if you look at the TPS:
- top wire is 5v live feed (to red wire on old 1.6 loom)
- centre wire is GND (to black/green wire on old loom)
- bottom wire is signal (to green/white wire on old loom)

I have checked continuity on all of the wires back to the relevant pins on the ECU plugs and they all read good.
I have also set the two jumpers on the ECU board: " set to 'linear’ jumper on the baseboard (J_TPS1), install the jumper on ‘J_TPS2’"

One thing that puzzles me is that when the ignition is turned on I would expect the top wire to show a 5v feed but none of them are showing any voltage?

carl4x4
Apprentice
Posts: 3
Joined: Thu Mar 14, 2019 6:38 pm

Re: signals to TPS help please

Postby carl4x4 » Thu Mar 14, 2019 10:05 pm

so I've just done a resistance test using a multi-meter and it looks like I had the wires confused, apparently you can check by:

If you're not sure which connection on your TPS goes to which wire, check it with an ohmmeter/multimeter. Observe the resistance as the throttle opens and closes. Each pair of pins will behave differently:
The resistance between the 5 volt and ground pins will remain constant.
The resistance between the ground and signal pins will be low with the throttle closed and high with the throttle wide open.
The resistance between the 5 volt and signal pins will be high with the throttle closed and low with the throttle wide open.

looks like I had the signal & 5v wires the wrong way round, need to wait for the weekend to try out my hypothesis. Still doesn't explain the lack of 5v though when ignition on?

sunny2019
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Joined: Fri Mar 15, 2019 9:56 am

Re: signals to TPS help please

Postby sunny2019 » Fri Mar 15, 2019 9:59 am

I vote on the question or comment. I will also make comment if I feel my words contribute to the discussion and has not be completely duplicated by someone else's words. I am interested in all of the discussions, although I may not be able to post my opinions because my workplace and I have to wait until the end of the day to make my comment or provide an answer.
shell shockers unblocked

carl4x4
Apprentice
Posts: 3
Joined: Thu Mar 14, 2019 6:38 pm

Re: signals to TPS help please

Postby carl4x4 » Mon Mar 18, 2019 9:51 am

Moral of the story is don't believe everything you read on the internet :oops: With the switched wire the TPS readings popped up straight away on the PC and I was able to calibrate the TPS using the wizard.
So best to use a multi-meter and test it yourself.


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