Expert help needed on 1993 TPS voltages.

[fujioko]

Hi ‘ya folks,

I’m using a 1993 fuel injected Festiva engine in a Mazda Miata. This is sort of a backwards B8 to B3 swap The goal is better gas mileage.

I’m attempting to modify the Miata wire harness to work with the Festiva engine and computer.

Since I’m using a Miata harness… I need to make sure I don’t cross a few connections. I have good documentation on the Miata harness, however the Festiva documentation is lacking some details. The sticky 92-93 wiring diagrams are the same as my manuals.

The throttle position sensor (TPS) has three wires. I figured out the ground but the remaining two wires are not defined.

Specifically I need to know which wire is the reference voltage and which wire is the signal.

Perhaps someone could use a DVM and measure the voltages on a real Festiva.

The wires I need measurements from are the following:

Yellow wire from ECM pin 2L
And
Yellow/black wire from ECM pin N


Here is a simple procedure description. Try this at the TPS.

Turn ignition on but don’t start the engine.

Ground the black lead from the DVM to the engine block.

With the red DVM wire….

Use a safety pin and poke the yellow wire and record the voltage. Move the throttle a little and see if there is a change in voltage.

Then poke the Yellow/black wire and record the voltage. Move the throttle and see if the voltage changes.

Any help would be awesome!

Thanks

Jim

[wybnrml]

Yellow wire is Reference, Black wire is Signal and Yellow/Black wire is Ground. Hope that helps.

[fujioko]

Yellow wire is Reference, Black wire is Signal and Yellow/Black wire is Ground. Hope that helps.

Thanks for the input! I’m still having some difficulties with the published information.

According the manual the black wire is ground.

The manual indicates yellow and yellow/blk are the wires that lack definition. Could you double check your resources.

Thanks

Jim

[Movin]

Wups..check diagrams in other thread..