Solution for P0500 VSS speed sensor problem on Nissan Sentra 96 - Nissan Forum
B14 95-99 chassis 1995-1999 Sentra and 1995-1998 200SX

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post #1 of 23 Old Jul 10th, 2007, 04:35 PM Thread Starter
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Smile Solution for P0500 VSS speed sensor problem on Nissan Sentra 96

Problem: P0500 error code on Nissan Sentra 96. Speedometer works fine.

I'm posting the solution to this problem to help other Nissan owners on the Internet.

Solution: Since speedometer works fine, the problem is NOT the speed sensor (which is on the trans-axle and difficult to access and pull out). The solution turned out to be an intermittent open at a terminal on the back of the instrument cluster. Wiggling the wires to terminals 22 (R/Y wire) and 23 (R wire) and 21 (PU/R wire fixed the problem.

In retrospect, the loose terminal wire problem was probably caused by a person who hit me in rear with enough force to jiggle wire and slosh brain around in skull, but not enough to damage the resilient Nissan rear bumper.

To diagnose the problem, I did the following tests:

I first tested the PU/R wire running to ECM (engine control module. This wire carries the VSS signal. (There is a harness connector just prior to ECM that is easy to access on passenger side near ECM). Take multimeter and set to DC or AC volts; connect multimeter between ground (I use cigarette lighter outside metal for ground) and harness connector female terminal 1 with PU/R wire. Start up car and drive around a bit; voltmeter should read nonzero when moving and should increase with increasing speed.

If read zero, then VSS signal not reaching ECM. Gain access to back of instrument cluster (easy to do, consult Haynes manual) and perform same voltage test except connect between ground and terminal 21 (PU/R wire ) on back of instrument cluster. If get nonzero reading, then you have an open between speedometer and ECM.

NOTE that the voltage tests were done with all harness connectors connected. You can connect to wires from rear of harness connectors.

Verify by checking for continuity of PU/R wire running from speedometer and ECM (the two terminal you just did voltage tests on). Remember to disconnect harness connectors at both ends to isolate from rest of circuit. If continuity checks out, then possible PU/R wire is being grounded. Check for continuity between PU/R wire and ground (remember to reattach all harness connectors but disconnect battery. If connected to ground, then isolate location of grounding. Reconnect battery.

For me, continuity checked just fine between ECM and speedometer. I was going to replace speedometer until I decided to measure voltages at instrument cluster which was enough to jiggle wire back into place.

To finish up, I reset the OBD error code (use OBDII software on portable computer). Then use OBDII software to monitor VSS. It was nonzero while driving around, indicating all was fine with VSS.
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post #2 of 23 Old Feb 7th, 2008, 01:56 PM
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Thanks for the info, I will try it. Having the same problem.. replaced vss with no luck.
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post #3 of 23 Old Sep 23rd, 2008, 04:31 PM
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Just got a P0500 for 1st time today. My speedo has been randomly quitting for a year. When it goes out, I lose function of the speedometer, odometer, and cruise control (if on). A quick smack to the dash or snapping the odometer reset button usually fixes it, so I know it's a loose connection in the cluster somewhere. Now I know which ones to look for. Thanks! I'll post any confirmed results if I get any.
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post #4 of 23 Old Sep 27th, 2008, 01:26 AM
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I got same exact problem on my Nissan Sentra 96 GXE.

Speedo/odometer just suddenly stops/drops to zero
and then by jiggling/pushing in/out/holding in the mileage trip reset button - usually speedo will come back to life. But dreaded CEL Light is ON - cant pass Mass state inspection with that on. (as you know)


How do you remove or pull off/unclip/detach the wire bundle connectors on back of the cluster gauage ? So I can get at wires and do/try what you did.

Is there any info on this forums or pics showing/how to do that ?

Where can I get/see the tech specs on all the wires/signal (ie voltage, ohms etc ) for all the pinouts on the speedo cluster gauage ?

Online here anywhere ?
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post #5 of 23 Old Dec 16th, 2008, 11:04 AM
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I had similar trouble with the speedometer and odometer not working. Sometimes it would others times it would not. Sometimes the speedometer needle would bob up and down.

Dealer told me the speedometer head needed replacing. They had just replaced it 13 months ago when I first got the car with a non-working odometer.

I found out from a speedometer repair shop to try the following simple test to confirm if it is not the speedometer before removing it from the car and mailing it in for repair.

Drive the car about 40 MPH and when the speedometer is not working try to set the cruise control. If the cruise control will not work, make all sorts of noises but will not set, then check / replace the speed sensor in the transmission and / or the wiring from the sensor to the computer.

If the cruise works and the speedometer does not, check the wiring from the computer to the speedometer and those connections.

Mine turned out to be the speed sensor's nylon gear was worn down so far it was not contacting the transmission gear anymore and only the ATF was pushing the gear on occasion. Usually only when the trans was cold and I guess the fluid was thicker.

Replaced the sensor and not a bit of trouble with the speedometer in three years now!
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post #6 of 23 Old Apr 1st, 2009, 04:25 PM
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Just found this thread this morning. Very helpful. Am still having trouble figuring out what is giving me a P0500 code on my 96 Sentra. Maybe someone can suggest something?

My problem: Speedo works intermittently. I can pretty much control its function with a series of whacks to the dashboard... which is cool with me, however, I need to pass my upcoming emissions test.

What I've done: I replaced the speed sensor 2 weeks ago. The same problem has persisted. Just today I took out the cluster and checked the connections. Everything seemed fine with the exception of the connector directly behind the speedo seeming a bit loose. I pressed it in to the best of my ability. Finally, I took it for a spin and did the ol cruise control test mentioned above in which I found that when the speedo loses function I CAN NOT engage cruise control. When speedo is working, cruise works just fine.

Ideas of what I could try next?
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post #7 of 23 Old Apr 1st, 2009, 05:59 PM
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By your description of the cruise control test it must be a connection problem between the speed sensor and the computer. I would have said the speed sensor but you said you replaced it. Did the connector look OK? Disconnect the negative battery terminal first and then I would check these connections at both the speed sensor and the computer. There is also a possibility that you have a wire in that harness that is broken or corroded. It could be a positive wire or a ground wire or ground wire connection someplace too. The ground problem might be under the dash since you said you can hit the dash to make it work etc. I would probe around under there and loosen / tighten all grounds I can find and also look for oxidized or corroded connectors while you are at it. An oxidation buildup can insulate a ground terminal from the metal frame it is screwed into even when the screw seams tight. Loosen and re-tighten the screw or bolt can often do the trick to reconnect the terminal to the grounding part of the car.

Last edited by etepsnewo; Apr 1st, 2009 at 06:02 PM.
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post #8 of 23 Old Apr 2nd, 2009, 10:22 AM
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Thanks for the tip. I'll be testing and checking tomorrow.
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post #9 of 23 Old Apr 5th, 2009, 05:08 PM
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nissan had a recall on this. i had the infamous P0500 when i got my 95 sentra. loosten (check for corrosion) the screws on the back of the cluster and make sure theyre tight that fixed 95% of them for the others clusters were usually needed (if speedo doesnt go out - that would be VSS) if necessary i think some have used aluminum foil or something to fix if there's a broken wire on the cluster but im not a motherboard engineer lol
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post #10 of 23 Old Jun 14th, 2009, 05:22 PM Thread Starter
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Recian gave an excellent suggestion which will solve most P0500 errors in which the speed sensor is working. Unscrew the instrument panel and then tighten all the small screws on the back of the instrument panel. My first message indicated that jiggling wires while measuring voltages cured the problem; in reality, tightening the screws is what cured the problem.

Taking off the instrument panel is easy. Two screws hold the plastic piece in front of the instrument panel. Unscrew these and then pry off the plastic piece (plastic tabs are what you are prying out). Unscrew the 4 screws that hold the instrument panel to chassis. Note that the steering wheel needs to be in the 12 o'clock position to get the plastic piece out from behind the steering wheel.
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post #11 of 23 Old Jun 14th, 2009, 05:27 PM
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yea Nissan had a bulletin relating to this issue in 95 and 96 .. honestly they had like 2 pages of bulletins and recalls for this car, especially the engine issues but tightening the screws was the first part of the bulletin because it went to the cluster THEN the ECM so u could have no cruise or anything if it happened but the speedo would still work ok
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post #12 of 23 Old Jul 18th, 2009, 08:38 PM
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Had erratic RPM indications with my NZ new 97 Nissan Sentra Q. Removed the instrument cluster as per recomendations below and tightened all the screws on the rear. Didn't work the first time around, but when I riggled the Orange/Black wire on the instrument cluster connector with three wires the RPM indication operated correctly, I pulled the connectors a second time to take a closer look as sometimes when wires are terminated with connector contacts they can be crimped onto the wire insulation with only a couple of wire strands touching the actual contact causing intermittant operation, I was unable to remove the contact from the connector so couldn't confirm if this was the case, in addition I undid the screws partially on the rear of the instrument cluster and then re-tightened them to make sure they were clean. Once all was back together I turned on the engine and it all appears to be working fine.
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post #13 of 23 Old Jul 18th, 2009, 10:59 PM
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I finally fixed this once and for all about a year later... I unbolted the cluster and removed all the connectors so I could work in it on my bench. I then removed the clear plastic front window, loosened and retightened all the screws on the back, sprayed all contacts with good deox spray (no residue), and also sprayed deox into the hole around the odometer reset button and worked the button in and out, reconnected all the plugs and also pushed/forced the wires into the backs of the plugs once secure, reinstalled the plastic window. Problem solved.
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post #14 of 23 Old Jul 23rd, 2009, 06:46 PM Thread Starter
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DeOxit is a strong (but expensive) deoxidizer that worked well for me when solving intermittent electrical problems on my 96 Nissan Sentra. Regular contact cleaner from the auto store was insufficient in fixing the intermittent electrical problems at connectors. I bought the liquid form (put on like nail polish) as opposed to spray form.

Disconnecting each terminal from every connector on the back of the instrument panel is probably overkill (in addition to being time consuming and requiring an 'extractor tool'). This is where the spray form of the deoxider would come in handy; spray the deoxidizer into terminal holes without disconnecting connector terminals.

Anyone know why Nissan didn't just use a regular circuit board on the back of the instrument panel, as opposed to the flexible green plastic with copper tracings with another clear sheet of flexible plastic on top of that? There are over a dozen circular plastic holders holding down the flexible circuit in addition to the large number of screws. It looks lame and it seems you could eliminate all the screws and holders by just using a solid circuit board.

Do newer Nissans use electrical connectors less prone to oxidation failure? I just looked at a 2006 Nissan X-Trail FSM and it looks like they are using the same types of connectors for power.

As guitartec mentions, between the screw tightening and deoxidizing all of the electrical contacts, the problem is solved (and won't reoccur for a long time).
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post #15 of 23 Old Jul 24th, 2009, 01:26 AM
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Removing cluster connectors

Actually, I highly recommend removing the cluster so you can get at all the screws and connectors, especially if you're not sure where the problem lies. It only takes a minute to remove all the plugs, no extractor tool is necessary (at least on the 96 Sentra) and it's impossible to get them confused when reconnecting them as each plug only fits its counterpart.

DeOxit is good for the electrical connections, but Radio Shack also sells a deox spray that works well and is much cheaper. Make sure the deox spray you use leaves no residue, as the residue (lubricant) attracts dirt.

Last edited by guitartec; Jul 24th, 2009 at 01:28 AM.
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