For several months now, the speedometer and odometer on my '93 4runner have only been running sporadically. It will sometimes work properly for a few days, but generally the needle will only pop up for a few seconds at a time. On a couple of occasions, if the speedometer hasn't functioned for a several minutes, the check engine light will also come on. But as soon as the speedometer fires up again, the light will go off.

The only thing I could think to do to diagnose was to take the gauge cluster apart and inspect the cable. It felt like it could be a little bit loose, but nothing terribly obvious. I sprayed some contact renewal on it while I was in there, but it didn't seem to make a difference. Any tips on how to diagnose this sort of thing?

 

You can easily pull the drive gear out of the transmission where the cable attaches and inspect the teeth.
If the speedo cable was an issue it would typically make horrible sounds, so I doubt that.
The next suspect is the speedo head itself.
I took my speedo head apart(actually not too bad to do) when my needle was bouncing a bit. i cleaned everything, but then went too far and added a very light oil. That messed everything up, making the needle peg out no matter how slow i was going. I had to diassemble everything and clean the oil off. Sadly, after all that, it still bounced a bit, just not as bad.

See what others post up.

 

The gear is plastic.
IF someone changed lets say the rearmost bearing and didn't do it right then the "lock" (Little ball in the shaft) for the metal "snail" gear will fall out into the tcase and then if will stip the plastic teeth ust enough to not work anymore.

Or it's the cable itself - all my Auto 4Runners have bouncy speedos The cable is too sticky.

 

thanks for the input so far. just to clarify, I wouldn't classify the speedometer is being "bouncy" but rather, it seems to cycle between functioning and not functioning. sometimes days in either state, but usually not more than a few minutes in either.

one small development. just yesterday I started noticing that if the speedometer is functioning correctly, and then goes into non-functional mode, I have seen the dash warning light come on for the "rear anti lock." I have also noticed that the engine might of 'skip' or 'jump' (hard to describe) when this happens. I don't recall this happening before, so I don't know if I screwed something up when I removed the gauge cluster. maybe one of the cables didn't like being disconnected and reconnected?

 

No, i got it. I just thought it best to mention why I took my speedo apart so you don't think I was chasing the same symptoms. Your issue may be in the head, just for a different reason.
you can take the speedo out and bench test it using a drill and running it at different speeds.

 

If you want to save time, money, and frustration, buy a GPS speedometer. Amazon is loaded with them at various price levels. Some even let you set the mileage, and display the mileage too.

 

If it were just the speedometer I wouldn't be too concerned, but now that I'm starting to notice additional symptoms I'm a bit worried that there is a more serious underlying issue.

 

Is it a mechanical speedo? Else check all your ground connections first. Take em off, clean, back on.

 

Sorry for the delay in responding. I didn't use the vehicle much over the winter.

Yes, as far as I know it's mechanical, although I'm not sure how to tell exactly, I'm just assuming. It's the OEM speedo.

I do have some updates on the speedo issue. The other symptoms were getting worse, with the vehicle losing power while driving. I suspected it might be a bad alternator, so I brought to Autozone and had it tested, and it did come back as a bad alternator. I replaced that, and as far as I can tell that DID fix the intermittent speedometer issue. Does that make sense to someone that knows more about a failing alternator and function of the speedometer?

However, I was hoping the new alternator would also fix the random loss of power issue, but unfortunately that does not seem to be the case. But from doing a bit of driving and experimenting in the driveway, it seems to me to be some kind of electrical issue. The loss of power seems to be triggered by turning things on and off. So things like the hazards, turn signal, or headlights. It doesn't happen every time, but that always seems to be the trigger. Since this is a different issue, and since the speedometer seems to have been resolved with the new alternator, I am going to start a new thread. Thanks to everyone for their input.

 

My '94 has the electronic speedometer. Based on comments I've heard here, there isn't just one year when they all changed over. It's easy enough to tell; on the back of the transfer case, do you see a fitting with electrical wires or one with what looks like flex conduit?

My speedometer sender failed with just the symptoms you describe. It would read accurately, then suddenly drop to zero for a few seconds, then pop back up. At least one person here reported success cleaning the sender, but they are now available at RockAuto for not a lot of money.

The speedometer not only drives cruise control and the transmission, but other things inside the ECM. GPS may help you avoid speeding tickets, but it won't help your truck run.

 

Thanks for the input. From what you describe, it sounds like my speedo might be electric. I'm pretty sure I recall an electrical plug going into the back of the gauge cluster. Cleaning the plug (the sender?) was the first thing I tried but that didn't seem to help. But like I said, the new alternator SEEMS to have resolved the issue. Now I just need to figure out why I'm occasionally losing power when I use my headlights / hazards / turn signals...