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Chris (aka-Moose)
Chris (aka-Moose), Auto Technician
Category: Toyota
Satisfied Customers: 947
Experience:  16 years of experience
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Have a1989 Toyota Land cruiser 6 cyl. when reving engine it

Customer Question

have a1989 Toyota Land cruiser 6 cyl. when reving engine it goes up to about 2000 rpm and quits like running out of gas. fuel pressure is at 45 lbs, code #42 comes out so change the tps. same results
Submitted: 1 year ago.
Category: Toyota
Expert:  Dj replied 1 year ago.

Hello and thank you for trusting us with your question. I'm DJ.

There's two parts to the throttle position sensor. One part is like a volume control on a radio. The other part is an on-off switch.

The on-off switch or the wiring to it is the problem.

There is a brown-black wire that goes to the TPS. Right next to it should be a yellow-white wire but that could vary.

This is the wire to the idle switch in the TPS. Probe that wire with a thin needle or a lapel pin. The idea isn't to poke a big hole in it with a probe. We need to measure the voltage. So hook the black lead of your volt meter to the negative post of the battery and the red lead to the needle that's stuck in the yellow-white wire.

With the key in the RUN position, the voltage should change when you first start to open the throttle. I expect that you're not going to see any change.

Try this test and let me know what you find.

The ECU turns off the injectors when the throttle is closed and the engine RPM is over 2000. The ECU thinks you're engine braking and coming down a hill so it shuts the fuel off.

If the switch part of the throttle position sensor isn't correct, it will turn off the injectors when the engine hits 2000, just like what's happening with your truck.

Please test the voltage on the yellow-wire or the wire that's right next to the brown-black wire on the TPS and let me know what you find. We'll figure it out from there.


Customer: replied 1 year ago.
ok, Ill let you know as soon as I can get it tested. Art
Expert:  Dj replied 1 year ago.

Ok Art. I'll be here.


Customer: replied 1 year ago.
with key on open throttle we get 5V. Close throttle 0V.
Expert:  Dj replied 1 year ago.

How far does the throttle have to move to get it to switch?

It should only take about 1/16" of cable movement or less to make the switch.

Customer: replied 1 year ago.
it goes to 5v as soon as it opens then jump to 12v at full throttle and. dropa all the way down to 1 to 2 volts wide open
Expert:  Dj replied 1 year ago.

I'm confused. Isn't full throttle and wide open the same?

What is the voltage with the throttle closed.

Half way open?

Throttle all the way open?

Customer: replied 1 year ago.
0V at closed throttle, around 7 to 9 volts at halfway, spike over 12V throttle all the way open
Expert:  Dj replied 1 year ago.

How far do you have to open the throttle to see the voltage jump from zero to 7 volts?

Should be about 1/16" inch.

Customer: replied 1 year ago.
well it starts at 5 volts with throttle slightly open and keep rising as the throttle opens more
Expert:  Dj replied 1 year ago.

That just doesn't sound right. What is the color of the wire that you're testing?

Is there a brown-red wire on one end and is this wire right next to the brown-red wire?

Customer: replied 1 year ago.
top wire is green and red, second wire is green and black .third wire is green white last wire is brown and black. The wire tested wa
Expert:  Dj replied 1 year ago.

Brown black is ground. Green white is the wire that we should be testing. Is that correct?