Speedo Problemo

[race4fox]

Ok, so me and my friend are crusing my RB20 powered S13, and the speedometer decides to start wiggin out. Ill just be driving and itll quick working, then if I hit a bump, it comes back on... So Im thinking a short somewhere right? Wrong. No bare wires or anything that could cause a short. So I check to see if I get a reading from the plug (8-pole)next to the fuse box under the hood. I get a reading from the side of the plug that goes through the fuse box (and to the speedometer), but not through the side that goes to the VSS. It only has two wires, black and green (no trace). Now before I go buy a VSS from AutoZone for $57 (pt. # SU4660), does everyone else think that it is my VSS and not something else?

I wasnt sure what forum to put this thread under, so relocate it if ya need to.

[90_rb20]

Hey man. Had the same problem. If this motor has ever had an electrical issue, or ANY kind, it will cause this. My alt went out had the same problem, it was the VSS. Later I had an overcharging problem and it was the VSS.

I can tell you now, just replace it. Coming from a fellow RB owner that did what you did already and some, this is the problem. Good luck bro.

[race4fox]

Thanks man, I had to make sure. My only other problem is the tach, I have a R33 tach, actually two of them, and I cant get either of them to work. But thats another headache for another day...

[90_rb20]

Hmm, you cant get it to work at all? Thats odd they usually work just fine.

Theres a 10resistor fix for the stock 240 tach, and the r33 should solve it all together.

[race4fox]

Yeah I tried a 0-10k ohms variable rate resistor, it made it work, but was wayyy off and jumped when I hit about 4000-5000rpm. So I installed one R33 tach, since they mount differently I soldered a wire with an "eyehole" on each of the three wires, and matched them accordingly. Thats when I got nothing at all. So I tried to re-install the stock tach w/ resistor setup, and it doesnt work now either. I have no idea whats goin on now. Should I be getting a resistance reading off of the yellow wire with a red trace (signal) and the ground? Should the car be running when I test this or just have the key on?

Oh and get this, I drove my car just a while ago without the speedo working, I got frustrated and hit it and it started working again. Violence FTW! So Im guessing I just have a loose connection on the back of the speedo, but that doesnt explain my whole plug resistance test theory...

So tomorrow Ill take apart the dash to tighten up those screws on the back of the speedo, and see what I can do with that tach. I may borrow an aftermarket tach from AutoZone just to see if Im getting a signal, and then go from there...

[race4fox]

Ok, havent had time to update so here it is now:

I took the cluster out the other day, checked all the wires and screws on the back of the cluster, they all seemed to be perfect working condition. So, I put it back together, and the same problem. I needed a working trip meter, so I bought a cluster out of an 89, installed it, and still get the same problem. Something else I noticed, my temp gauge also freaks out on me, if I hit the brakes/headlights/turn signals - anything electrical - the gauge moves. So Im thinking I have a bad/loose ground somewhere, but Im not sure where. Any ideas as to where would be a good place to start?

When I first got the RB running, the ignition switch wouldnt turn the car off all of the time, and after about a week, it worked like it should, so I never replaced it. Does anyone else think it could be the contact points in my ignition that are wearing out?? I think the ignition is close enough to feel the violent haymakers Ive been sending it...