Digital speedometer problem...

[dave8775]

:helpI have a 1993 Nissan 240SX SE with a digital speedometer that has recently gone blank on me. It started going off on occasions and now it is almost always off (though it sometimes still pops up again and goes out a few minutes later). When it is on it seems to report mileage accuratelly. Does that rule out a bad 'speedometer cable' or speed sensor? If that was out would the speedometer simply display '0' or would it go blank.

I have a feeling it is probably some contact, but since I do not know much about cars (though I am making an effort to learn) I thought I'd ask here if anyone has had a similar problem and knows how to diagnose/fix it. I have a friend who works on my car and he suggested that I perhaps need a new 'instrument cluster'... but I am hesitant cause it is expensive, and I feel it is not the problem. Could it be a bad contact as I suspect? Where would be the most likely location for such bad contact to occur?

BTW, the car has almost 180K, but has worked fine really! (apart from these minor issues).

Do you have any suggestions/comments?

Thank you for your help. I did try to search on the forum and did not find any solutions regarding this matter.

Cheers,David

[NISTECH]

http://www.nissaninfiniticlub....45498

[L0sT]

yo nistech, is this the TCM?

[NISTECH]

yepand yesterday I repaired one sucessfully. do me a favor and pop the cover off at the connector end slide the circuit board out of it. Take a picure of the non component side of the board try to make it a larger picture then that one and post it I will edit the picture to show where it needs to be repaired and explain how to do about it. You need to be very very skilled with a solider iron though. or you could damage the circuit board. I cant see the last five digits of the part number on your unit there but it should be 40P00??

[NISTECH]

by the way from the dealer its like 285 bucks.

[L0sT]

what is the non component side? i tried once to open the dam thing and it wouldnt come off, felt like it was stuck to someting inside...iduno lol

yea, i just got my digi cam so i can take bigger pics now, ill have them up soon if i can take off the thing. hmm, i have some experience soldering from school, but ill see.

....but 285!?!?!?!?! holy ****!!!!!!:eek:

[NISTECH]

you have to release the four tabs along the side of the case at the connector end to open it. the side of the circuit board that doesnt have IC's, transistors,resistors,diodes. the side with just the soilder mounds ,snap a shot of that side.

[IvoryJ30t]

hey nistech, real quick [it kinda relates to speedos] i used to have a list of the different VSS colors and ratios for nissans. you wouldnt happen to know a link or have that info, would you?

[NISTECH]

no I dont. Dont really have a use for the info on the job. we dont do any drastic moding to cars.

[IvoryJ30t]

yeah that what i figured. you would just replace it, you dont care what the specs are.

i gotta dig it up.

[L0sT]

ok, i went down to the junkyard and found a 93 240sx and snatched up the TCM, i connected it and still my cluster dont work..still only the tach. btw, the part number is 28550 40F00. i took some pics anyway and ill post themup soon

[NISTECH]

what exactly doesnt work?

[L0sT]

its a digital speedo w/hud btw

the speedo, odometer, and tripmeter dont work, and the HUD. it doesnt light up or anything

the only things that work are the tach (but still dont light up) and those lights for engine check, seatbelt, doors etc etc..

so far ive replaced the circuit board thing on teh back of the cluster (my mechanic replaced it) and since he replaced that, my clock doesnt work now either.

[NISTECH]

I just so happen to have the wiring diag on my desk here for a 93 with HUD . let me look it over see if I can see a possible other cause... do you have night illumination in it?

[L0sT]

nope, nothing lights up

my car is a 92 btw....93s came with digi/HUD clusters?

im not sure what yearmy cluster came from, but i know its not the original cluster

[NISTECH]

this diagram doesnt have the illumination circuit it is primarily the warning lighting. I have the illumination one on my box at work will lok it over tomorrow and get back to you. yours may have the soldier problem in the speedo head itself.