Scottzilla Posted June 4, 2009 Share Posted June 4, 2009 (edited) Problem solved! Updates/answers are in blue. Long story short, I had a problem with the wiring going to my throttle position sensor. I spliced in some new connectors and wires from the yard. Now I'm noticing two things about the AT: 1- It seems to be a bit sluggish shifting. Going up it waits until higher RPM than it used to. (Power switch/light are off). I actually started noticing this before my latest bout of rewiring. 2- Auto-power doesn't seem to work any more. When I stomp on the gas the Power light used to come on but now it doesn't. I'm not sure exactly when it quit working. Does the tranny use the TPS to know how much gas you're giving it and determine where to shift? Yes! Does it use it to know when you've stomped on it and activate Auto Power? (or is there another switch somewhere) Yes. It uses the CTP part of it (the connector that is molded into the TPS itself). In the tranny troubleshooting document the two halves of the switch are called the "full throttle switch" and the "idle switch". I don't know for sure that it doesn't use the kickdown switch too but if the idle and full throttle switches aren't hooked up right Auto Power won't work. Why are there two connectors on the TPS? The one on the pigtail connect to an internal potentiometer and you can read the value with a meter. I can't tell what the other one on the body of the TPS is for. The pigtail one provides a linear value based on how much you've depressed the accelerator pedal and is referred to as the "throttle sensor" on the tranny troubleshooting doc. The one that is part of the TPS is for the "full throttle switch" and "idle switch" (see above). Basically I'm wondering if my new TPS or one of the connectors are bad or if my tranny is starting to have problems. It's got plenty of red fluid and was rebuilt not that many miles ago. It turns out that the two outside wires for the CTP had been reversed so the tranny thought I was flooring it when I was idling and vice-versa. She's shifting like she used to now. Does anyone know how to pull codes from the TCU without having an OD button? (I have a power button only). I do (now)! You use the power button. When the instructions call for the OD button to be off put the button in "Power" mode (out) and when it calls for OD on put it in "Auto" mode (in). On rigs that have the power button and no OD button the power button is connected to the pin on the TCU connector where the magic document says that the OD button is supposed to go and there is nothing connected to where the power button is supposed to go. Why didn't I think to try the power button in the first place you ask? Well I did, but since the CTP wires had been reversed it was sensing that I was doing the pedal part wrong. To test the theory I went through the whole procedure but reversed the pedal pushes and releases and it finally started blinking out error codes. (#3 TPS- even though I'd pretty much figured that out by then). Note for me: don't do wiring when I'm really sleepy. Note for Nissan: quit using the same color wire for different signals that go to the same sensor. Edited June 17, 2009 by Scottzilla Link to comment Share on other sites More sharing options...
88pathoffroad Posted June 8, 2009 Share Posted June 8, 2009 Yes, the TCU uses the TPS to determine WOT and idle, shift speeds etc. Have you tried adjusting the TPS? It can be adjusted quite a bit. Link to comment Share on other sites More sharing options...
Terrano1992 Posted June 8, 2009 Share Posted June 8, 2009 Why are there two connectors on the TPS? The one on the pigtail connect to an internal potentiometer and you can read the value with a meter. I can't tell what the other one on the body of the TPS is for. The other one is for CTP (Closed Throttle Position) switch. Link to comment Share on other sites More sharing options...
Scottzilla Posted June 11, 2009 Author Share Posted June 11, 2009 (edited) The other one is for CTP (Closed Throttle Position) switch. Good to know. Thanks! Yes, the TCU uses the TPS to determine WOT and idle, shift speeds etc. Have you tried adjusting the TPS? It can be adjusted quite a bit. Just tried it. I managed to make it worse, but not better (it was already adjusted all the way one way). I'm starting to wonder if my new wiring harness is no good either. I tried a whole different TPS (again) Edited June 11, 2009 by Scottzilla Link to comment Share on other sites More sharing options...
Scottzilla Posted June 13, 2009 Author Share Posted June 13, 2009 Does anyone know how to pull codes from the TCU without having an OD button? (I have a power button only). Link to comment Share on other sites More sharing options...
Scottzilla Posted June 17, 2009 Author Share Posted June 17, 2009 It's amazing how much you can learn by crawling around in your rig with a meter for a couple of hours. I got my problem solved. See first post for details. Link to comment Share on other sites More sharing options...
Kingman Posted June 17, 2009 Share Posted June 17, 2009 Note for Nissan: quit using the same color wire for different signals that go to the same sensor. Nissan didn't design any of the fuel injection system and related systems for the TBI, Bosch did. It's just been licensed for use under the Nissan name. I find the wiring for everything to be extremely cheesy and hard to decipher. Nissan should have definitely picked a better company. Link to comment Share on other sites More sharing options...
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