VR wiring,TPS wring

Forum for discussing how to install MicroSquirt(TM), choose and troubleshoot sensors, wiring, and communications for MicroSquirt (TM) and MicroSquirt Module(TM).
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109e
MegaSquirt Newbie
Posts: 24
Joined: Wed Apr 28, 2010 12:56 pm

VR wiring,TPS wring

Post by 109e »

Hi great forum, just in process of installing Microsquirt onto a ford 2.0 zetec, can anybody tell me which wire i connect to the crank sensor, and how to connect it,i.e if its the shielded wire do i connect the shielded part to ground? also does anybody know which wire is which i.e sensor, ground,5v on the TPS, tried a resistance test but still cannot work it out
Many thanks in advance, Chris
Matt Cramer
Super Squirter
Posts: 910
Joined: Sat Jul 03, 2004 11:35 am

Re: VR wiring,TPS wring

Post by Matt Cramer »

The shielded wire and shield go to the crankshaft position sensor.

The easiest way to check a TPS is to unplug it and put an ohmmeter on its pins. Observe the resistance as the throttle opens and closes. Each pair of pins will behave differently:

The resistance between the VREF 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 VREF and signal pins will be high with the throttle closed and low with the throttle wide open.

If your sensor behaves like this, it will be pretty straightforward to connect it to Megasquirt.

If the resistance jumps from infinite (or near infinite) to near zero, you have a switch type throttle position sensor, or possibly a seriously defective potentiometer type TPS. These do not provide very much information that Megasquirt needs, as it can tell if you are at idle or full throttle by the MAP sensor information. You can still use MAP based acceleration enrichment and ground the TPS signal pin through a resistor.
Matt Cramer at DIY Autotune
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