Dan_E_Boi84

iTrader: (3)

First off I will like to say that the Speedo Sensor is new... Plus I've elimanated the cluster by plugging in a different one. However... The speedo is eradic. It'll go from the speed that im going to zero or between. I'm sure it's not a wiring problem cause I can make it drop to zero by just barely pressing on the gas... then when i press further down to put the car under a load it jumps up to the speed that i'm going. It's seems as if it's in sync with the load on the tranny...it's a wierd problem... I'm about to upgrade phones so one of these days I'll upload a clip of the problem for you guys. HELP PLEASE. As said before I've replaced everything in the schematic of the speed sensor except for the ECU. Any Ideas?? I do have a code for the Speed sensor circuit reading is zero volts at times so that means that it's either the circuit or the ECU. PLEASE HELP

Nealoc187

iTrader: (23)

I had to do some speedo trouble shooting once but it was a long time ago, I'm trying to remember what the FSM says the votage output of the sensor is supposed to be. I think it was 0V at rest. If so, maybe the speedo gear on the differential is bad? The speedometer gear on the differential is plastic in our cars, and it is concievable that a piece of debris in the transmission could mess it up in such a way that it would only manifest itself under light load but as you give it more gas to increase the load the case and transmission internals flex such that the speedo sensor engages the gear again and then it works. It's a pretty long shot but it could explain the code for zero volts in the speedo circuit at times and also your intermittent problem...

Dan_E_Boi84

iTrader: (3)

There would have to be wear on the speedo sensor in that case then but there is not. I had replaced it with a new one and there was absoulutely NO change. FYI you're right about the voltage. 0 volts at 0 mph...then it sends a square wave in correspondence to the actual speed. Appreciate your advise though Nealoc187.

96max_manSE

iTrader: (3)

i have the same problem with mine it can be alot of difrent thing like abs speed sensors the speedo itself circuitry problems and even in the transmission plays a role in this.

Dan_E_Boi84

iTrader: (3)

Well if you figure out the problem with yours then post it please because it's starting to get on my nerves.... What kind of things have you tried to correct the problem???

Dan_E_Boi84

iTrader: (3)

Ok...Here's a thought... tell me what you think... I think my ECU is bad... due to my code for the speed sensor circuit reading zero part or all of the time. My speedo jumps due to the ECU backfeeding a ground signal to it which makes the voltage drop to zero which is 0mph... So... my next step to diagnoses woulld be to eliminate the ECU from the equation by just disconnecting the wire feeding to the ECU. This will cause the Speedo to work properly...(which at the moment will just verify that that part of the circuit which includes the Cluster and Speed Sensor and associated wiring to be working as designed.) This shouldn't hurt anything due to the fact that the car doesn't shut off when my problem occurs. So... if in fact this works then the next step is to definitely replace the ECU...(cause it's hard to believe that ABS has much to do with the speedo due to it being it's own circuit)(nothing against what you said 96max) So... if you think this will work or otherwise let me know... or if you have any other ideas post them. Thanks....

kc10fish

iTrader: (1)

ck the harness. had a rat/mouse eat mine down there. no kidding.

Dan_E_Boi84

iTrader: (3)

Eh...I really don't think it's a wiring problem...it just doesn't act like it...but thanks for the advise...

dgeesaman

iTrader: (10)

All these intermittent symptoms you point out scream wiring problem. Now sure why you'd think otherwise.

Dave

Dan_E_Boi84

iTrader: (3)

Well... I'm getting a camera phone shortly... when I get it I'll video the problem and you can experience what I'm talking about. I'm sure it's not a wiring problem. I have this local shop around here and they work on nothing but nissans and he said that he hasn't seen this problem before. His suggestions were the gear inside the tranny(which goes along with Nealoc's theory or a bad ECM(my theory) so...next step...since on problem requires complete teardown of the tranny... then i'm going to try to prove my theory.

dgeesaman

iTrader: (10)

If it's the speedo gear in the tranny, just pull the speedo sensor. If the speedo gear in the tranny, there will be damage to the speedo sensor gear, or the sensor will simply be broken.

If the sensor is damaged or broken, then you are almost guaranteed that your tranny would need to come apart to fix it. I know from experience.

Dan_E_Boi84

iTrader: (3)

The gear shows no signs of damage so.... that points to the ECU??...I can get one for 45 dollars so... I'm gonna try out what I said earlier and disconnect the wire going to the ECU to see if the Speedo works without it...so...we'll see!! Hopefully that'll be the end of it and I'll feel comfortable buying the part knowing that it's the prob.

Dan_E_Boi84

iTrader: (3)

Ok so I disconnected the Cruise control module and drove it and the problem still existed. Then I cut the wire going to the ECM (which served two purposes...#1 to help diagnose and #2 to disable my speed limiter.)and.... the problem is still there...
According to the schematic... there is one thing left... the transmission control module...Now...I don't know if I disconnect just the wire for the speedometer signal if it's gonna cause any major concerns but... I think that's my only option. Does anyone know where it is by any chance? Thanks for everybodys advice. But I'm still on the grind to find a cure for this sickness my car has come down with.

Dan_E_Boi84

iTrader: (3)

Sorry... The question was... Does anyone know off hand where the transmission control module is at on a 99 max. Don't want anyone to get confused. I wasn't clear in my post above.

Dan_E_Boi84

iTrader: (3)

OK...So... I've gotta put my foot in my mouth. As you see I've had this problem for awhile. I kind of put it on the back burner for awhile and really didn't believe it was a wiring problem like Dave had suggested. I mean... it was intermitent just not in the sense of being something that happened from time to time but a constant problem with a personality to it. For instance... I could ALWAYS make it work when I wanted it to... It ALWAYS acted the same everytime I pushed on the gas... I just KNEW it was a bad module that had an internal problem or something. Well... guess what... it was a wiring problem. I just recently got hired on with a nearby Nissan Dealership in the parts department here in Jacksonville and got with the techs and one guy hooked the Consult up to it drove it around the building and told me that the TCM was getting a signal from the speed sensor but not the ECM. So.... I figured it was because I had disconnected the wire going to the ECM as a "tweak" to shut off the speed limiter. So... another tech walks up to me afterwards and asks me what the previous tech had said and i told him and he askes me to pop the hood and with a couple of tugs at the engine harness next to the passenger strut tower where it bends he sends me back on the road and says "see if that's a temporary fix" and sure nuff... The speedo is working close to perfect... a couple of glitches but a massive improvement. So... sorry to anyone I didn't listen to. Just another case of my hardheadedness. Thanks everyone for all the advise!