vTPS wiring link G4x

[adlmx5]

Hey all!

Im struggling to understand how to wire in my vTPS.

I have the link G4x designed for my 1990 Mazda MX5. The manual says that the MX5 doesn’t have a factory fitted TPS but it does, just not a vTPS. On other ecus it’s simply a matter of plugging in / wiring in a vTPS into the factory loom and selecting the right input in the ecu. I’ve plugged the vTPS into the stock wiring loom but the ecu is not receiving any signal. I didn’t think any additional wiring would be needed.

 

Kind Regards 

[adlmx5]

Ok, I think I’ve wrapped my head around this if someone can confirm.

On the stock wiring harness pinout the TPS comes in on pin 21 which is NC on the LinkG4x.

Would it simply be a matter of depinning it and wiring it into AN Volt 1 on pin 7? 
 

[Adamw]

The 1600 MX5's only have an "idle switch", connected to ground and pin 46 and a WOT switch connected to pin 21.  If this is your car then there is no 5V at the idle switch so there is nothing to power a 3 wire variable TPS.  So if you have a 1600 model then the easiest option is to use an expansion haness to get the 5V and an analog input to the new TPS sensor.  

The 1800 models have a factory 5V TPS and these need nothing further, it is connected to AN Volt 1 ( pin  7).  It looks like the pinout in the manual has a typo as it shows pin 7 as O2 sensor, but it is in fact TPS on 1800MX5 and GTX.

[adlmx5]

The stock harness does have 5v, signal and ground at the tps as seen in the photo attached. So there shouldn’t be any additional wiring needed for a 3 wire vTPS. I guess all I’m asking now is basically, I need to move the pin from the stock ecu location to any AN volt, either pin 6 or 7 right?

[Adamw]

That pic is not of a factory 1.6 MX5 TPS pinout.  As I said above they only have a ground, a WOT signal and an Idle signal.  Most likely that pic you show is taken from either a megasquirt or speeduino plug-in manual in which they do a weird fudge at the ecu pinout and send 5V down one of the original signal wires.  Obviously not a great idea when the factory connects that same wire to ground, so it is a nice way for someone to short out the ecu on first poiwer up if they dont read the manual before plugging it in.

You can do the same if you wish by splicing the WOT signal wire (pin 21) to the 5V (pin 8) and move the idle signal wire to pin 7.  

[adlmx5]

Ok thanks, I’ll splice pin 21 to pin and and move the signal wire to pin 7 and report back.

Thanks for the info

[Frijimouth]

On 5/14/2021 at 8:17 PM, Adamw said:

That pic is not of a factory 1.6 MX5 TPS pinout.  As I said above they only have a ground, a WOT signal and an Idle signal.  Most likely that pic you show is taken from either a megasquirt or speeduino plug-in manual in which they do a weird fudge at the ecu pinout and send 5V down one of the original signal wires.  Obviously not a great idea when the factory connects that same wire to ground, so it is a nice way for someone to short out the ecu on first poiwer up if they dont read the manual before plugging it in.

You can do the same if you wish by splicing the WOT signal wire (pin 21) to the 5V (pin 8) and move the idle signal wire to pin 7.  

Any confirmation that this worked?