Throttle position sensor - Page 2

silviagod · #11 05-01-2009, 10:29

I am waiting to see if Apexi email me back if not I may try to make a potential divider with some resistors and hope it doesn't effect the signal doing to the automatic transmission control unit.

30psi · #12 06-01-2009, 16:58

The S12 auto TPS is simply 2 switches in one. It provides a full throttle signal and an idle signal, with no variance in between.

If you use an S13 one, it has an additional plug come from the rear of the the unit then provides the variable signal.

Only issue, is that you may need to supply 5v (guess) to it for the signal to be similar to how it would be on an S13.

The answers to your problem are in the S13 service manual. Rather than look at the wiring diagrams if you look at the tests for the TPS it should show the switching side and the potentiometer side of things.

silviagod · #13 06-01-2009, 17:06

Thanks 30 PSI. The throttle contacts on my S12 Auto and on the other one I have do have an additional plug underneath with a voltage that varies from 0.5 Volts to 6.95 Volts depending upon the position of the throttle and I was hoping to tap into that signal for the SAFC II. I also haven't had a reply from Apexi yet.

30psi · #14 06-01-2009, 17:09

So your auto TPS also has the variable bit on it, but uses 7V as a base? Didn't know that, I thought it just had the idle and full throttle switches.

I guess Apexi is only happy with a 5V base?

silviagod · #15 07-01-2009, 08:04

The input voltage to the TPS is battery voltage and I have just got an email from a friend in America who has telephoned Apexi for me. The reply he got was as follows:
In regards to your question about the throttle position sensor reading 6.95V
and if this would damage the SAFC2 unit. This would not damage the unit. The SAFC2 unit can only read a 0 - 5 V signal, so therefore, the only downside to your TPS sensor reading 6.95V is that the SAFC2 will not be able to read/monitor voltage above 5V.

So I can use the wire but anything in the last fraction of travel of the throttle will not be measured correctly. That should do for me because the car seems to be running rich enough at that point on the existing fuel map.