TRAC Code 47

[Louie7]

I'm trying to get a handle on some acceleration issues and idle issues.
So, my '94 LS400 (with Trac) throws the code 47 (when reading Trac Codes, of course).
I'm told that code 47 means: When idle switch is ON, sub-throttle position sensor signal is 1.45V or higher - That's a bit vague...

And that's where I'm confused. My understanding is that the sub-throttle position sensor, like the primary TPS should be seeing 5V from the ECU. But the code is telling me that the signal is 1.45V or higher. Does that mean the signal from the ECU is too low and should be higher? I haven't done any testing with a volt meter yet...I need a bit more clarity on what I'm shooting at. For instance, where is the 'idle switch, what turns it on or off and when?

Thanks... any comments appreciated. Louie7

[LSPaul]

I went through similar issues last year with my car. 

My guess is that the ECU is at fault in your case.   Replacing the TPS sensor for the TCS brought no joy for me, even when adjusted properly.  The throttle position sensor is both a variable resistor and microswitch. 

The solution in my case was to replace all the electrolytic capacitors in the engine ECU (plenty of writeups, and some good places out there that do 'em).  I did mine at home, buying a kit of the correct electrolytics off an eBay seller, carefully unsoldering and replacing one at a time.  Once back together and in the car, the codes cleared and all was good.

To test voltages, one has to either carefully pierce the insulation of the wiring to the TPS or else rig up a jumper that one can connect a volt-ohm meter to.

Best,

Paul