TPS bypass verification

[JRZ]

Was hoping some of you pro's could confirm how to bypassing the TPS/ TCS since the search function didn't turn up anything solid. My TPS is broken so I have it unplugged for now. Just tired of looking at the TCS and engine check lights. I will eventually get to fixing it later. My thought is that I need to splice the TPS on the opposite side of the throttle cable to the TPS wires at the bottom of the tb (hopefully the colors of the wires are the same). TIA

 

[d.n]

I'm not a pro, but have you fixed this one yet? If not, the wire colors are different (just look at the connectors, you'll see they aren't the same). If memory serves I think the pin locations are flip flopped too (1-3, 3-1 perhaps?), but please don't quote me on that. You'll want to just hook up a little test harness to the TCS side TPS and measure the voltages and compare them to what's in the service manual for the normal TPS. You really do want to make sure that TPS is functioning properly anyhow rather than just splicing wires and doing some guess work. It doesn't take long at all to do this (5min if you have some spare wire and small female connectors)

I already taped / ziptied my wiring up, but if you absolutely can't figure it out, let me know and I'll can pull it all off and trace the wire colors back for you

 

[JRZ]

Thanks for the reply D.N. No I have not fixed this yet. Simply couldn't find any more info on this. Since the wire colors might be different and I need to use a multimeter to test, I better just leave it alone for now. I'd feel like asking too much for you to have to go through all the trouble of taking off the intake to check. If you eventually recall how the wires are tapped, I'd really appreciate your help.

 

[d.n]

I just realized you have a 6speed / late model NSX. Mine is a 91 so the wiring could very well be different so I wouldn't trust my wire chart without measuring on your car. If you weren't on the other side of the country I would help you measure it, but it is really fast to measure :smile:. A cheapo volt meter is in the $10 range at radio shack (bought mine at Sears).

Rough steps to measure. NOTE: you can strip some wire cover on each wire to measure, but I really dislike cutting into the factory harness at all so instead, I like to jumper the plug to the sensor with some wire and measure voltage at the wire.

- To jumper the sensor to the plug, you'll want some small female connectors (or alligator clips) for this (3x) and some wire (18ga is fine). Unplug the TCS TPS. Jumper all three wires from the TCS TPS to the connector that you just unplugged using some wire (those female connectors work really well for this, you can just stuff the wire into socket on the other side). Turn the car on (position 2, but engine off) and measure according to what's in the service manual.

If memory serves, the three wires are:

- power
- common/ground
- signal

the voltage between signal and common/ground will be ~0v with the throttle closed and swing up to 4v at WOT. It's probably easiest to find power first by measuring between one wire and a good ground at a time. When you see one that jumps up in voltage with the TB closed, you have the power. The one that the voltage swings when you open and close the throttle is your signal. The last wire will be the ground. Once you have your color codes, on the TCS TPS you can then match this up with what's in the service manual under the TPS trouble shooting.

Good luck! The car will run and start up way better when you fix this and it's not too hard to do (much easier in fact than this explanation would have you believe).

 

[Mac Attack]

All the time and effort you put into bypassing the main TPS you could put into replacing it then! :biggrin:

I have a '92 with TCS delete. Like d.n, I did the TPS splice so I could get rid of that honkin' TCS steppr motor on the TB. Nice instructions d.n

Dave

 

[JRZ]

Sorry forgot to mention it's a 92 with a NSX-R trans. If only I did have an 95+. The tps for those are about $25 which I have bought and returned because the gear turned the opposite direction. We pre-dbw guys seems to need to get the whole tb from the dealer for $1600 to get the right tps. I did find a used one on ebay for less but, don't want to take a chance on it being bad so deleting is a better option for now.
Thanks again for the detailed instructions d.n. Now I feel confident in doing this. Your the man.

 

[Mac Attack]

$1600 Jeez, I've never priced it. Sorry.

Have you seen the service manual then since you have a '92? It shows both sensors as being 0-5V output, and even shows a curve of the TPS voltage output as a function of position. But, it doesn't show the output of the other sensor, which you'd have to confirm (which has already been done, so you just need to get the wire splicing right).

Good luck!

Dave

 

[JRZ]

Haven't seen the manual Dave. But, it looks like simple splicing and testing of power/ground will do the trick. Will do the signal test just to confirm. Thanks for both of your help.

 

[angus]

How about an aftermarket TPS? The ones from blox are good.

 

[JRZ]

The three wires were consistent with each other and the colors were very similar besides the middle one. Tapped into the harness and started the car up after I plugged back in the clock fuse. Lights were off and idled fairly normal for a cold engine so I was happy and tightened everything up for a test drive. Unfortunately bypassing the tps did not work. The lights came off but, the original problems took it's place. The car runs like crap again. Hesitates, bogs, irregular idle when gas steadily. I had to unplug the harness under the intake this time since the tps is already spliced up to it. I don't know if there maybe something else I'm not aware of causing this . Back to square one.

How about an aftermarket TPS? The ones from blox are good.

Thanks for the tip Angus but, I've looked before and they all list for 95-05. I even try calling several sellers to physically tell me which way their tps turns and either they are not too eager to make a sale or just simply not familiar and answers " I think they all just turn clockwise". After the same results from the third seller, I stop searching.

 

[Mac Attack]

The three wires were consistent with each other and the colors were very similar besides the middle one. Tapped into the harness and started the car up after I plugged back in the clock fuse. Lights were off and idled fairly normal for a cold engine so I was happy and tightened everything up for a test drive. Unfortunately bypassing the tps did not work. The lights came off but, the original problems took it's place. The car runs like crap again. Hesitates, bogs, irregular idle when gas steadily. I had to unplug the harness under the intake this time since the tps is already spliced up to it. I don't know if there maybe something else I'm not aware of causing this . Back to square one.

Sorry, I'm confused now. In your 1st post you said you were just getting the TCS and check engine lights.

Now you said the warning lights went off briefly after the TPS splice but then the car runs like crap again?

Did the warning lights reappear after this?

Did you say you had to completely unplug the TPS wires via the harness under the intake? If so, did that fix your problem?

 

[JRZ]

Sorry Mac. I originally had a crappy running car that was traced to the tps. Once the tps was unplugged, car ran good again. So that's why I wanted to do the bypass to get rid of the tcs and check lights. Now both harness is unhooked. Warning lights are back on and car runs good again.

 

[Mac Attack]

Wow, that seems weird. Only thing I can think of would be to find a local owner that you could swap TPS's or ECU's with for a check. What codes did you get previously?

Look at the troubleshooting beginning on page 11-50 of the service manual. You also need to read the TCS section. Page 19-114 is trouble shooting for the pedal angle sensor.

Dave

 

[d.n]

Did you measure the tps output to make sure the "other" one isn't bad too? I guess perhaps that's not necessary since it would throw a code if it was bad. At least mine did.

 

[JRZ]

There was one owner in my area but, he seemed to have disappeared. Will read up on what the sensor under the intake does to understand more. Unplugging the tps solved my issues. Now that it is bypassed and spliced with the one under it and gives the same problems, I'm stumped. I did test the tps and it didn't give any readings. If I could find my original tps that I hacked up to recalibrate, I'd bypass the one from the bottom and tap into the tps to see what happens. I have looked quite a bit already and may of simply threw it out as I thought I was getting a new one then. I'll live with the lights for now. Thanks.