digital speedo not working

[93 teg]

k first of all this isn't even my car im what you would call a hobby mechanic. i fix what i can for a couple of bucks. well my buddy has a 91 240sx and lately he has been having all kinds of problems for starters his gas tank fell off and we had to try to strap it up with metal banding because the rear frame is in the way of one of the strap bolts and the other one just won't budge. and since the tank fell his trunk release and gas lid release aren't working. tried pulling the wire with a pliers but nothing happened. finally the problem im actually trying to fix for him is the digital speedo isn't working. sometimes when he starts it up it works for a couple seconds then fades out. tach works most of the time. checked all the fuses and his odometer still works somehow?? also if anyone thinks he needs a new cluster what is the easiest procedure to get the dash off without taking the whole interior apart?

another amusing detail,,, he said he doesn't like his exhaust job he had done on it (too raspy) i checked it out. no cat and they put on an xerator turbo muffler... lol no backpressure on an NA car.

[TuRbOS13]

Man I've had that same problem, I heard it may have been my capacitor in the speedo so I picked up one from an electronic store n soldered it on the correct place n it still didn't work. It would come on for about 10 seconds when I started up my car then it just unwillingly shut off for some odd reason......I called a tech n he said it was the rearboard, so I ordered another digital speedo and kept having the same problem.....Now I tried an analog speedo and it did the same thing, but this time since it wasn't digital n couldn't shut off, the needle would just work for about 10 seconds when I drove, but then it would drop and sometimes shoot back up to the right speed then shut off again............I've done plenty of research n have come to think its the speedometer sensor.......I'm hooking it up to a computer at a tech shop to find out whats wrong, I'll get back with you

[fgooga]

Had the same problem..... Turned out to be a faulty connection from the sensor. Bypassed the sensor, spliced the wires together and works now. You might want to check your wire connections all along from the sensor connected to the transmission its just your digital speedo that isnt working.

[TuRbOS13]

Turned to actually be the speedometer, about the first 4 didn't work so I got an analog speedometer out of a 89 240 and spliced all the wires together and now its good as new!