Where's the speed sensor?
Thread Starter
Joined: Oct 2004
Posts: 132,419
From: 1600 Pennsylvania Ave, Wash. DC
Where's the speed sensor?
I got a couple of codes that are saying my speed sensor is bad. I know it's on the tranny, but the pic in the haynes is teh ghey and is really, really, really bad. Anyone have a pic that can point it out? Also, the Haynes says to take it to the stealership for diagnostics, but it would probably be cheaper just to replace it considering that there's a 99.99999% chance it's just bad with as many miles as I have. Codes are P0720 (Vehicle speed sensor) and P1574 (Automatic speed control device).
I would tell you but the diagram in the FSM sucks too. The ASCD code is cruise control related, and is probably because the ECM is picking up a bad signal from your speed/revolution sensor. Unless its TCM related. Just speculating, I don't even have an AT. 
Thread Starter
Joined: Oct 2004
Posts: 132,419
From: 1600 Pennsylvania Ave, Wash. DC
Originally Posted by Puppetmaster
I would tell you but the diagram in the FSM sucks too. The ASCD code is cruise control related, and is probably because the ECM is picking up a bad signal from your speed/revolution sensor. Unless its TCM related. Just speculating, I don't even have an AT.
Thread Starter
Joined: Oct 2004
Posts: 132,419
From: 1600 Pennsylvania Ave, Wash. DC
Here's a novel idea: I'll fix the damn thing and take a pic of it, post it here and a mod can link this to the code list in the stickies! What a great idea! I'm so smart!
Dealer just told me that the ABS wires are also called the speed sensors...
The genius that installed my Stillen Front Lip managed to rip out my front passenger ABS wire and he just let it go and handed it back to me like that
The genius that installed my Stillen Front Lip managed to rip out my front passenger ABS wire and he just let it go and handed it back to me like that
Thread Starter
Joined: Oct 2004
Posts: 132,419
From: 1600 Pennsylvania Ave, Wash. DC
We found the problem(s) last night. There were two plugs not connected: the first was the speed sensor that led to the SES. THe plug was actually broken, so for now it is glued together until Nissan decides to send me a new one (3-4 days). The second was the tranny ground. We found the problems at Redline who also, for the time being, shares the shop with NHR transmissions (they build racing trannies among other things). Rob at NHR has to be by far the best mechanic that I have ever spoken with. Not only did he find the loose connections in 2 minutes flat, he also told me quite a few things that I thought I would share:
First off, our trannies absolutly need to be grounded. There is a 2-3 volt loss from the tranny case to the motor. What this means is that any electricity that builds up in the tranny and needs to be bled off tries to find the path of least resistance. In the case of an un-grounded tranny, it's through the bearings and drive shaft. This leads to arcing in the bearings and will eventually lead to tranny failure. Nissan has a pretty good ground, but this gives another great reason to use a grounding kit and to ground the tranny.
Secondly, the drop resistor mod is very, very, very bad. It'll kill your tranny pretty quickly if it is used often.
Thirdly, the speed sensor is definitly necessary. Without it, the computer goes into a limp mode for the tranny. It'll shift weird (mine rode in a lower gear than necessary and slipped on the 1-2 shift), the cruise will not work and it'll also break the belts internally. In other words, if you throw the codes above, get it fixed ASAP. When I get the new speed sensor, I'll take pics of the location. It's not easy to get to, though, as you have to get under the car at the back of the tranny to change it. There's a 10 mm (surpised?) bolt that holds it in place. Once the bolt is removed, there's an O-ring that seals the sensor and can be tough to pull out. If you replace the sensor, replace the O-ring as well.
First off, our trannies absolutly need to be grounded. There is a 2-3 volt loss from the tranny case to the motor. What this means is that any electricity that builds up in the tranny and needs to be bled off tries to find the path of least resistance. In the case of an un-grounded tranny, it's through the bearings and drive shaft. This leads to arcing in the bearings and will eventually lead to tranny failure. Nissan has a pretty good ground, but this gives another great reason to use a grounding kit and to ground the tranny.
Secondly, the drop resistor mod is very, very, very bad. It'll kill your tranny pretty quickly if it is used often.
Thirdly, the speed sensor is definitly necessary. Without it, the computer goes into a limp mode for the tranny. It'll shift weird (mine rode in a lower gear than necessary and slipped on the 1-2 shift), the cruise will not work and it'll also break the belts internally. In other words, if you throw the codes above, get it fixed ASAP. When I get the new speed sensor, I'll take pics of the location. It's not easy to get to, though, as you have to get under the car at the back of the tranny to change it. There's a 10 mm (surpised?) bolt that holds it in place. Once the bolt is removed, there's an O-ring that seals the sensor and can be tough to pull out. If you replace the sensor, replace the O-ring as well.
Nightmare = Reality
Joined: Nov 2005
Posts: 718
From: Waterford, MI
Originally Posted by GBAUER
We found the problem(s) last night. There were two plugs not connected: the first was the speed sensor that led to the SES. THe plug was actually broken, so for now it is glued together until Nissan decides to send me a new one (3-4 days). The second was the tranny ground. We found the problems at Redline who also, for the time being, shares the shop with NHR transmissions (they build racing trannies among other things). Rob at NHR has to be by far the best mechanic that I have ever spoken with. Not only did he find the loose connections in 2 minutes flat, he also told me quite a few things that I thought I would share:
First off, our trannies absolutly need to be grounded. There is a 2-3 volt loss from the tranny case to the motor. What this means is that any electricity that builds up in the tranny and needs to be bled off tries to find the path of least resistance. In the case of an un-grounded tranny, it's through the bearings and drive shaft. This leads to arcing in the bearings and will eventually lead to tranny failure. Nissan has a pretty good ground, but this gives another great reason to use a grounding kit and to ground the tranny.
Secondly, the drop resistor mod is very, very, very bad. It'll kill your tranny pretty quickly if it is used often.
Thirdly, the speed sensor is definitly necessary. Without it, the computer goes into a limp mode for the tranny. It'll shift weird (mine rode in a lower gear than necessary and slipped on the 1-2 shift), the cruise will not work and it'll also break the belts internally. In other words, if you throw the codes above, get it fixed ASAP. When I get the new speed sensor, I'll take pics of the location. It's not easy to get to, though, as you have to get under the car at the back of the tranny to change it. There's a 10 mm (surpised?) bolt that holds it in place. Once the bolt is removed, there's an O-ring that seals the sensor and can be tough to pull out. If you replace the sensor, replace the O-ring as well.
First off, our trannies absolutly need to be grounded. There is a 2-3 volt loss from the tranny case to the motor. What this means is that any electricity that builds up in the tranny and needs to be bled off tries to find the path of least resistance. In the case of an un-grounded tranny, it's through the bearings and drive shaft. This leads to arcing in the bearings and will eventually lead to tranny failure. Nissan has a pretty good ground, but this gives another great reason to use a grounding kit and to ground the tranny.
Secondly, the drop resistor mod is very, very, very bad. It'll kill your tranny pretty quickly if it is used often.
Thirdly, the speed sensor is definitly necessary. Without it, the computer goes into a limp mode for the tranny. It'll shift weird (mine rode in a lower gear than necessary and slipped on the 1-2 shift), the cruise will not work and it'll also break the belts internally. In other words, if you throw the codes above, get it fixed ASAP. When I get the new speed sensor, I'll take pics of the location. It's not easy to get to, though, as you have to get under the car at the back of the tranny to change it. There's a 10 mm (surpised?) bolt that holds it in place. Once the bolt is removed, there's an O-ring that seals the sensor and can be tough to pull out. If you replace the sensor, replace the O-ring as well.
EXCELLENT EXCELLENT info! I used to see that drop resistor mod floating around and it always seemed a bit bogus to me to do anything, considering under WOT it's not softening the shifts anyway. I wonder if i grab some leftover 4Ga. from my car audio stuff and make my own grounding cable for the tranny would it be just as good if not better than the grounding kit?
Time to bring the dead to life. So I got the P1574 code went to Nissan and was told to change the sensors. Did that and still no luck I also checked the wires too. What else could it be? Changing the speedo didn't help. I think it may be a ground that I'm missing. Someone please help me!!!
Junior Member
Joined: Jul 2008
Posts: 78
From: BROOKLYN
I went and got the same code at speed control device my car feels different and lazy in the gears I think it has something to do with this I also have a po442 evaparation leak how much does this sensor cost ??
Senior Member
Joined: May 2005
Posts: 415
This "black rubber plug" is a reverse switch for your backup lights. That i know for sure. First time i heard it was a speed sensor.
I wanna dig this one up seems no one ever had a clear answer and i have a code p1574 also. my speedometer reads about 30 when going 60 and my criuse is inop.i pulled the sensor on the back of the transmission and it looked ok,not craked or anything,anyone have any ideas?
I wanna dig this one up seems no one ever had a clear answer and i have a code p1574 also. my speedometer reads about 30 when going 60 and my criuse is inop.i pulled the sensor on the back of the transmission and it looked ok,not craked or anything,anyone have any ideas?
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