Speedometer acting up.. need help! :(

[AJM0617]

Hi, the speedometer is acting up on my 92 FJ80 ever since I bought it last November 2011. I started a thread here a while ago about this issue, and people were telling me that it's my speedometer cable.. or test my cable.. well I tested my speedometer cable by hooking it on a wireless drill.. everything works fine.. it stayed on just bellow 30mph. thats moving the wire around while spinning.. So I don't know now what is causing my speedometer going to 110mph even though I just started accelerating from traffic light. (my LC can do 0-110 mph in 2 seconds) sometimes the speedometer is working fine. but a lot of times it goes straight to 110 mph even though I just accelerated.
could the problem be the gear thats attach on my transfer case where the speedometer cable is hook underneat the car? what is that part called?

Please help me on this.. I'm getting tired of driving around not knowing my actual speed other than 110 mph..

Thank you in advance..

Aron

 

[jamisobe]

Get a GPS and use it's mph function while you figure out your speedo.

Maybe it's the speedo gauge itself? Get an instrument cluster from someone parting out a truck. Not sure if all the years are the same.

 

[therealg]

I had a similar problem to yours. my speedo would jump to all different speeds, then one day it just stopped moving. My trip and odometer work fine so I know the cable is good. I was told by CDAN that it's probably the gear at the gauge side of the speedo, which is not made anymore. I need to tear my gauge cluster apart to be sure but that makes sense to me. Maybe you're dealing with something similar.

 

[Hoosier Daddy]

You can pull that little gear out of the transfer case and examine it pretty easily. I think that is not likely to be your problem though.

Any odd noises when the speedometer acts up? Does it act up only under certain conditions or at certain speeds?
Can you turn the cable wire by hand, and if so, is it smooth?

The electric drill may not be replicating the conditions under which the speedometer acts up, so it may not actually rule out the cable or instrument panel as a cause.

 

[diego355]

I simply decided to not pay attention to the speedo, mine jumps up and down like a lowrider caprice as I acclerate but in a range of 10km/h up and down. Its a 3FE so its is normal to be slower than everyone else, no speeding tickets for me. The odometer is accurate so I wonder what it could be?

 

[CJF]

When it jumps, is it like a spike?

Could be that the cable's getting bound up and then lets go all at once.

If you really want this fixed, you ought to replace the cable first. You *may* have other issues as well, but the cable is the most likely cause, as they've been shown to wear out.

 

[AJM0617]

No.. it doesnt really jump. Back and forth. It just goes to 110mph all the time. And when its working properly, when I shift from P to R and Back to P again, it starts acting up again.. or sometimes when its working properly, let say im cruising on the freeway, everything is working good then I take the exit and stop on the light, when i take off it goes back to going on 110mph again.. so it seems like when its working properly, everytime i shift to reverse and back to drive, it getz mess up again. Or when cruising then come to a complete stop then accelerate again, it goes to 110mph how do i know if the gear by the T-case is working properly or not?

Thanks guys, i really appreciate all the replies..

 

[MoGas]

This is the only place that I have used for years when I have a speedometer issue. They also happen to be the place that calibrates all the police car speedos in the valley.

Give them a call.

Dicks Speed O Tach Phoenix
4325 N 7th St
Phoenix,AZ 85014
(602) 279-6463

 

[prerunner84]

It's either your speedo it self going bad or your speed sensor check the speed sensor gear if it's in good shape then I think that's your two possibilities

 

[smug01]

I had a similar problem after a HG replacement. Turned out to be the speedometer ground cable was not attached properly. If I remember correctly, it attaches to the intake manifold near the PHH.

 

[AJM0617]

I had a similar problem after a HG replacement. Turned out to be the speedometer ground cable was not attached properly. If I remember correctly, it attaches to the intake manifold near the PHH.

Ill check that.. thanks man. what is PHH though?

 

[MoGas]

Ill check that.. thanks man. what is PHH though?

It's a 1FZ-FE thing.

 

[smug01]

Sorry. Pesky Heater Hose. It is a tough to reach coolant hose between the block and body. Near the brake booster.

 

[smug01]

Just saw you are a 92. Mine is a 97 so the location may be different.

 

[AJM0617]

Just saw you are a 92. Mine is a 97 so the location may be different.

Thanks man.

 

[jonheld]

I had a similar problem after a HG replacement. Turned out to be the speedometer ground cable was not attached properly. If I remember correctly, it attaches to the intake manifold near the PHH.

Not a likely scenario. 3FE speedometer is strictly mechanical.

The very first thing I'd do is remove, inspect, clean and lube the inner cable. This is a 5 minute job. Lot's of threads on this and it couldn't hurt.

The drill is pretty much doing EXACTLY what the speed sensor gear is doing. This is a VERY simple system. Transfer case output gear spins a small plastic drive gear which in turn spins the speed sensor which spins the speedo cable.

I'm going to ask a stupid question...is your rear driveshaft attached? I know I know. Had to ask.

It's possible that the speed sensor is fractured internally and filled with gear oil that is causing the second half to spin faster than the first. Just a wild guess, but another 5 minute job to verify. The speed sensor is held in place with a single bolt and pulls right out of the transfer housing without spilling any oil.

Other than that, the return spring on the speedometer itself could have broken. Next time it registers a higher than normal speed, give the top of the dash a good solid whack and see if it comes down.
Keep in mind that the "good solid whack" technique is something I use to keep all the dash bulbs on in my truck, so I take no responsibility for the outcome

 

[MoGas]

Depending on the temperature, you can also crack the dash by whacking on it.

 

[AJM0617]

Not a likely scenario. 3FE speedometer is strictly mechanical.

The very first thing I'd do is remove, inspect, clean and lube the inner cable. This is a 5 minute job. Lot's of threads on this and it couldn't hurt.

The drill is pretty much doing EXACTLY what the speed sensor gear is doing. This is a VERY simple system. Transfer case output gear spins a small plastic drive gear which in turn spins the speed sensor which spins the speedo cable.

I'm going to ask a stupid question...is your rear driveshaft attached? I know I know. Had to ask.

It's possible that the speed sensor is fractured internally and filled with gear oil that is causing the second half to spin faster than the first. Just a wild guess, but another 5 minute job to verify. The speed sensor is held in place with a single bolt and pulls right out of the transfer housing without spilling any oil.

Other than that, the return spring on the speedometer itself could have broken. Next time it registers a higher than normal speed, give the top of the dash a good solid whack and see if it comes down.
Keep in mind that the "good solid whack" technique is something I use to keep all the dash bulbs on in my truck, so I take no responsibility for the outcome

Thanks man.. I took the speed sensor out not too long ago just to see the plastic gear inside. the gear looks great. I'm gonna have to take it out again and check the whole thing. when I took it off the T-case, I didn't really disconnect the wire, I just checked it really quick. both of my driveshaft are attached lol.. how do I take the speedometer cable out? and also, can I take the speed sensor apart and maybe clean the inside of it?

I really appreciate your advises..

Thanks so much

 

[jonheld]

You'll see a knurled knob at the end of the speedometer cable where it screws onto the speed sensor. Unscrew the knurled knob and you'll see the inner speedo cable sticking out of the outer sheath. Grab it with a pair of pliers, pull and turn. The inner cable will pull right out of the sheath.
I loop it into a small clean bucket, spray it down with a solvent, wipe it clean. Then use a light spray grease and coat the cable well. Thread it back into the sheath.

The square end goes to the dash, the flatblade end goes to the transfer case.

When it wants to seat into the speedometer, give it a bit of push and twist. It'll go right in.

Done.

 

[AJM0617]

You'll see a knurled knob at the end of the speedometer cable where it screws onto the speed sensor. Unscrew the knurled knob and you'll see the inner speedo cable sticking out of the outer sheath. Grab it with a pair of pliers, pull and turn. The inner cable will pull right out of the sheath.
I loop it into a small clean bucket, spray it down with a solvent, wipe it clean. Then use a light spray grease and coat the cable well. Thread it back into the sheath.

The square end goes to the dash, the flatblade end goes to the transfer case.

When it wants to seat into the speedometer, give it a bit of push and twist. It'll go right in.

Done.

Thanks man.. Ill do that this coming weekend...