I have used my pc5 and the special cable from slp.

 

I don't have one, I was thinking with a multimeter - I will next season though. I can't believe this stupid TPS is keeping my sled in the garage this weekend. not 1 dealer out of 6 in my area has a tech working. there is no way in hell I'm risking this motor.

went from super low idle 1000rpm (no screen) to 2800 rpm. now won't pull 8250 rpm in the field. TPS is way out and I'm not looking for another lean burn down. I'm starting to think this TPS took my last motor out. same symptom - won't pull top rpm. but I drove it another 40 miles then pop.


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In the harness, in the black bag just above the voltage regulator, there is a plug labeled ECM PWR. An orange wire (positive) and a brown wire (neg) run to this plug. Connect a fully charged 12v battery to this and it will power up the ECM. You can then back-probe the TPS. I used sharpened paper clips to back-probe and a digital meter. Loosen the throttle cable all the way, you might even want to disconnect it from the throttle body. Now, back off the idle adjustment screw until it no longer touches the adjustment lever. Blip the throttle lever a few times. Your throttle blades should now be completely closed and you are ready to make the first adjustment.
There are 3 wires at the TPS. Red/White is the supply voltage, Blue is the signal to the ECM and the Black/Dark Blue is ground. Hooking up the meter to the Red/White and the Black/Dark Blue will get you the sensor voltage. It should be very close to 5v. Mine was 5.02v. Switching your probe from the Red/White to the Blue will get you to your readings for adjustment. For your first reading you want to see .700v. This is very important. If it isn't at .700v you need to loosen the screws on the TPS and rotate it until you get it there. Tighten the screws, making sure your setting doesn't change. Blip the throttle a few time and make sure it returns to the same voltage. If all is well at this point you can now set the throttle opening. The recommended setting is .930v-.950v. I set mine in the middle, .940v. You need to adjust the idle screw to set this. It's a bit tricky because as you tighten the lock nut on the adjustment screw the setting will change. Once set, blip the throttle a few times and make sure the setting stays the same. Adjust your cable and you're done. Also, I put a dab of clear silicone over the probe holes on the TPS to keep moisture out.
I made my own power-up cable from some 18ga. wire and a couple of bigger alligator clamps. I bared 1/4" on the other end and gave the ends a touch of solder for plugging into the ECM PWR connector. One thing I did notice was that, having electric start and using the sled battery to power-up, I only had to use the positive side of my harness at the ECM PWR connector. The battery neg and the ECM ground are connected through the chassis so, no need to use the neg side of my harness but, you will have to hook it up without ES or if you use a battery besides the one in the sled.
As for the meter, use the best one you can afford. I see you are an electrician so, you probably have a good one already. I have a couple of DVM's for servicing tube guitar amps and my most expensive one was under $100 and it worked fine.
This is how I did mine and it runs great.

 

so you only set the idle - there is no WOT setting?


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No WOT setting but, after everything is set you can check what the WOT voltage is for reference. Mine was 4.20v which I believe is what you want to see. Something else to check is the sweep of the TPS. Slowly open the throttle and see that the voltage rises nice and even. If it shows open anywhere you have a bad TPS. This is probably easier to see with an old style analog meter with a needle but, I think you would still see something with a DVM.

 

so if your TPS is off - can it cause a lean condition at WOT?


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Yes, it could cause a lean condition and all sorts of other driveability problems. To be honest, my sled ran pretty good before I checked mine. The only issue I ever had was the idle hanging kinda high before it came down to a normal idle. Like 2800-3000 rpm for a few seconds. My TPS wasn't out much but it wasn't totally in spec so, I used the process I outlined earlier. Runs great and the idle comes right down to normal without hanging up. Check it and let us know what you find.

 

You can check your TPS without going through the whole process. Power up the ECM, back-probe the TPS and see what you're at for idle voltage. Check the sweep. If the sweep isn't good you might as well get a new TPS and go from there. If the sweep is good then you might as well go through the process and set it up. At the very least, you've eliminated a potential source of trouble and you have peace of mind knowing it's set-up.

 

I'm going to the dealer tomorrow, but I will keep your procedure handy next time (hopefully there isn't a next time) I having issues


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A YouTube video on this procedure would be excellent!


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I thought about that as I was writing the description. I'm not going to tear into my sled just to make a video but, if I ever have to do it again I definitely will.

 

Very nice write up brad. Nice job.:beer:

 

I would caution you that MOST meters we use in the electrical industry are not accurate enough with this low of DC voltage . check the accuracy rating on the meter your thinking about using before you take your first ride or you may need some fresh aluminum parts.

 

Good point xc-mark. If you have access to a process meter (usually used by instrument techs) they should have the accuracy needed for this.

 

I'm going to ask the tech to keep a note as to how off the TPS voltage was.


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Let us know what he finds.

 

I must have got lucky then. Or got a good meter. :dunno:How inaccurate are meters at less than 1vdc? Thing is, I didn't invent this, guys have been doing this for a while. A lot of guys have built a 5v power supply and a TPS harness to do this. And most probably didn't use a process meter. If you have access to one then use it. And, now that you mention it, my buddy is a journeyman instrumentation tech and probably has one. Next time I do my TPS I will have to give him a call.
I think that this process is probably more accurate than building a power supply and TPS harness because, by powering the ECM, the reference voltage at the TPS is the same as if the sled were running. It eliminates the possible variable of the outside power supply.
If, in any way, this freaks you out or scares you then, by all means, go to the dealer and get it put on Digital Wrench. All I did was share what worked for me.

 

Brad,,, you friggin' ROCK:buttrock: My kids 11 800 assault developed a low until NO idle situation. Showed him your write up today,,,we just did it,,,,,perfect idle now:fistpump2::fistpump2::bc::bc:
Steve

 

this will be the 1st adjustment since the new TPS was installed a season and a half ago. I think the TPS got hit and budged a little when the new motor went in. had a low idle and intermittent "no perc" since. then things went downhill fast. high idle/low idle, hanging rpms, low top rpm.

weird thing is - it actually ran pretty amazing for 200 miles.
then the symptoms got worse. I checked the engine for possible lean damage - there is none of that. I was also breaking it in so the ez riding could have masked some of the issues. anywho I'll post after the dealer has the wrench on it.

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this will be the 1st adjustment since the new TPS was installed a season and a half ago. I think the TPS got hit and budged a little when the new motor went in. had a low idle and intermittent "no perc" since. then things went downhill fast. high idle/low idle, hanging rpms, low top rpm.

weird thing is - it actually ran pretty amazing for 200 miles.
then the symptoms got worse. I checked the engine for possible lean damage - there is none of that. I was also breaking it in so the ez riding could have masked some of the issues. anywho I'll post after the dealer has the wrench on it.

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Some or all of these above problems could have been caused by the throttle cable being improperly routed / stretched. As was later identified.

 

so TPS is set within spec. 41 codes for throttle cable to tight lol. the dealer will re route it. otherwise sleds fine.

 

Good to hear!:bc:

 

thanks for keeping us updated:bc:

 

alright so dealer just called, throttle cable is stretched and is now scrap, need a new cable.


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Reviving this TPS thread because it has some good info and I have a question. I'm about to test mine. I have a meter that's accurate to about 0.006 V at 0.7 V according to its specs. It's not a $100+ meter. The question I have is this: how precisely can the ECM read the TPS voltage? I've heard people complain about the digital wrench not being accurate enough and needing to use an expensive meter to really nail the setting. But wouldn't the ECM have its own tolerance range of reading the TPS voltage, and would it have anywhere near the capability of a $150 multimeter?
I'm going to use my cheap meter to check out the TPS and see what comes up. I have a hard time believing that a +/- 0.006 V tolerance band will cause a lean condition and engine failure. But I am open minded to the possibility. Seems to me either the sled runs better or it doesn't, and I can err on the high voltage (rich) side.

 

How does your sled run now? If you don't have any issues with it there's really no reason to mess with the TPS, unless you're just curious, of course. As for meter accuracy, here's a little write-up on the subject:

How to Determine Digital Multimeter Accuracy

The meter I used last year to set mine has an accuracy of +/-0.8%+5 digits. At .700v a .8% accuracy is +/- .0056v +5. This meter only reads as low as 1.000v so, my reading could be out by as much as .010v either way. Attempting to set a TPS at .700v might get me .690v or .710v or anything in between. I knew this going in and the fact that my sled runs great means I'm in the ballpark. I recently bought a higher-end meter with .1% +5 accuracy that reads as low as .1mv. This gets me much closer as my accuracy at .700v is now +/- .0012v, or, as my new meter reads, +/-001.2mv.
I'm not knocking your meter, just pointing out that you potentially can be out quite a bit. How accurate does the ECM read it? Great question. There are tolerances in everything and that might play a part in why some sleds run better than others.

 

My meter is the same accuracy as the one you described using last year. I understand how the accuracy rating works, but I was thinking the meter read to 0.1 mV when I typed up that post, which is not correct. So I have that same 0.010 V error band.

Anyways my sled was running a little funny, and on the rich side. I'm stock without a fuel controller so TPS checking and adjustment seemed to be the first course of action. So I went ahead and did it. It's running better now. This is the first I've had to deal with the TPS and my info source is threads like these and the service manual.
I moved it from 0.710 to 0.700 V based on my meter. Given the tolerance of the meter it could have been sitting at 0.700 to 0.720 V prior to adjustment. I'm satisfied with it now set at 0.700, which could be from 0.690 to 0.710 V.

I think the point here is that you don't need an expensive DMM to make an improvement, if an improvement is needed. You were thinking along the same lines I am now when you did yours last year. I was reading a thread on Snowest where everyone was getting worked up about having an expensive DMM or don't touch it, and that's really not the case if you know what's going on.
Knowing my sled is on the rich side and taking into account the accuracy of my meter, if I read 0.690 V I probably wouldn't bump it up to 0.700 V, for example.
I think that's a good point about tolerances like the factory TPS adjustment or ECM accuracy making some sleds run better than others. It's not what you'd think of right away.

 

Glad it worked out for you. I bought my new meter because I wanted the extra accuracy. I've had it for two weeks and your post gave me the kick in the ass I needed to get in the garage and check things out. It turns out my old meter wasn't too much out, .002v lower than my new one on every reading. Plus, I took pics this time for a "how-to" when I have a few free minutes to post one.