TPS issues/ no signal

MrIQR · Mar 9, 2019

Was attempting to adjust my tps when I lost all voltage at the tps connection plug. Sled had been not wanting to idle, fouling plugs and didn’t like to go into reverse, ran great other then that(little rich off the bottom).

Currently getting no signal or volts at tps plug.

IIRC signal was low from the ecu when I started.

What does this mean? Bad ecu?

Sled fires right up and idles great but check engine light is on, bogs and won’t rev over 7500(limp mode?) cel was not on when i started.

Where do I start?

MrIQR · Mar 12, 2019

Still can’t figure this out.

Tried another ecu and same results, no volts/signal at the tps plug.

Sheetmetalfab · Mar 12, 2019

MrIQR said:
Still can’t figure this out.

Tried another ecu and same results, no volts/signal at the tps plug.

Start inspecting the wiring harness.

Between the tps and ecu

MrIQR · Mar 15, 2019

I really dug and didn’t see any bad wires. Tested the voltaged again and boom had it. I was able to set both baseline and idle and now it’s dead again!

Must have a bad wire somewhere?

kgra · Mar 16, 2019

Test resistance or do voltage drop test on power wire between ecu and tps while wiggling harness to look for problem.

MrIQR · Mar 17, 2019

I am only looking for voltage at the tps plug, the only problem I am having is lack of voltage to the tps.

It comes and go’s for no apparent reason.

Are the wiring schematics posted anywhere? Need to be able to back track from the tps plug to its power source to figure out where it’s loosing power.

It has been consistently loosing voltage with two different ecu’s so I know it’s not the ecu.

I literally just had it running with no check engine light on(power to the tps), shut it off to put the air box etc back on and started it again, check engine light and no voltage. Most annoying problem ever, would never have this stupid problem with a carburetorated race sled.

diamonddave · Mar 17, 2019

What year is the sled? 800?

Try cleaning your main ground wires first. They are brown. Ground problems with the wad of ground wires attaching to the structure are normal with vary little corrosion. Wire brush and clean regardless.

I have not got my service Manual back so I can’t give you colors.

Three wires go to TPS.

One should be a 5 volt reference all the time.
One should be ground
One will be return voltage to the ECU depending on throttle opening. Generally 0.900 - 0.935 volts at idle and up to approximately 4.00 to roughly 4.30 volts max throttle.

You can put one of your probes at ground and check each wire to find your 5 volt reference. Once you find this one, you can then move your probe to find the ground. Then you can move the 5 volt reference probe to find which wire is return voltage.

MrIQR · Mar 17, 2019

When I get voltage all the tps wire voltages are in spec, that is not the issue. Random lost of all power to the tps in both directions is the problem.

Lastnight I had it running, tested everything, all were in spec still, no check engine light. Shut it off. Installed airbox, clutch cover etc, started it and the check engine light was back and no voltage on any tps wire in either direction. The tps circuit is completely dead.

Machine is a 2017 800.

Every connection and relay was clean but I cleaned and added dielectric grease for good measure. Still nothing.

The lost of voltage for the tps has truly became random and no viable reason.

Everything else works, lights, hand warmers, gauge, fuel pump, etc.. it’s only the tps circuit that lacks any voltage.

MrIQR · Mar 26, 2019

Voltage was back, started it, ran it at home a few times, no check engine light, seemed to run great. Let it sit for a few days and now the voltage is gone and engine light is back!

I have a service manual now but it does not have wiring schematics, tells you the which wire the tps wire is out of the ecu but that is it.

Is there anyway to avoid cutting the harness insulation off to too trace the tps wire?

Mxracer39 · Mar 27, 2019

The way I look for broken wires within a harness is to hook a multi meter up end to end.

In this case, unplug both connectors, and hook one multi meter lead to the tps connector and one lead to the ecu connector. You have to use spades on your test leads that will slide into the terminal and clamp your multimeter leads to them so you can leave the multimeter hooked up.

Set the multi meter to ohms. The wire should have under 1 ohm if it’s good. (Most read 0.2 to 0.5) Now start moving/wiggling or lightly tugging the wire from one end of the harness and follow it all the way to the other end while doing this. If you find the broken spot in the wire, the multi meter Reading will go way high, or read “OL”.

If your starting with a bad wire, ie 0 volts at the tps, you’re ohms reading will most likely be high or OL to begin with. Start following and wiggling the wire harness until you get a better or lower reading. Usually when I find a break in the wire, the multi meter reading will go all over the place as I’m getting closer to the bad spot.

Hope this makes sense and is helpful.

MrIQR · Apr 1, 2019

I tired a new wiring harness and it fixed my problem. I have my original harness cut open and visually don’t see anything wrong, not sure if I’m gonna to spend the time to figure where it failed.

Search

TPS issues/ no signal

MrIQR

Free Member

MrIQR

Free Member

Sheetmetalfab

Well-known member

MrIQR

Free Member

kgra

Well-known member

MrIQR

Free Member

diamonddave

Chilly’s Mentor

MrIQR

Free Member

MrIQR

Free Member

Mxracer39

Well-known member

MrIQR

Free Member

Similar threads