'94 Speedometer Stopped Working

[REDrum]

So I'm getting very erratic speedo action. >40mph it bounces up >100mph.

Seems like speedo sensor needs cleaning if not replacement. Just went to FSM and seems to be two speedo sensors? Anyone know which would be the culprit for erratic speedo on a '94?

Thnx

 

[Brentbba]

S/B the one on the transfer case.

 

[IdahoDoug]

Ditto. It hangs off the left side near the rear of the case and is actually kinda vulnerable to brush and light stuff. It is also prone to siezing up and ripping out the plastic teeth on the driven gear. Happily a simple 10 min replacement is likely good for another 17 years.

DougM

 

[Brentbba]

Ditto. It hangs off the left side near the rear of the case and is actually kinda vulnerable to brush and light stuff. It is also prone to siezing up and ripping out the plastic teeth on the driven gear. Happily a simple 10 min replacement is likely good for another 17 years.

DougM

Yep - driver side just in front of the rear drive shaft on the transfer case. It's held on with one 12mm bolt. Three wires lead into the sensor itself.

Well, mine seized and sheared off the 'key' (metal rod) on the sensor. The scarificial plastic teeth on the speedo gear in the t-case were just fine! Go figure. Shoot, either way it was going to run me $200 - either the sensor or having to put the OEM 32 tooth gear back in and spending $200 on the black box to correct the speedometer! Screwed either way! You are correct on the 10 minute 1/2 job tho!

Expecting a brown truck delivery from CDAN today so the speedometer will be up and running for Borregofest this weekend.

 

[REDrum]

thanks, local stealership got 247.32 outa me for it... Had to have this week

 

[REDrum]

So....I swapped in new speedo sensor. However....speedometer still erratic and bouncing up over 100MPH at speeds over 40MPH. But I went on two trips today each over 45 minutes. After about 30 minutes of driving speedo seems to settle in where it should be.

Thoughts?

Perhaps an exorcism?

 

[Brentbba]

Mr. Brown Truck arrived just in time Thursday. Got home from work with enough daylight to install the new sensor and housing to the tcase befor heading off to Borregofest Friday morning. THANKS DAN! Speedometer is working just fine. As usual, your advice, expertise and counsel (not to mention price and huge inventory of Landcruier parts available!) on what was needed to to the job right was right on and very much appreciated!

 

[fzjeighty]

I've got a 96 and my speedo/odo/trip ALL stopped working about 2 years ago. I did experienced a problematic ill effect . . . Basically, if I stopped the 80 quickly, the truck would stall, however if I very gradually came to a stop, the truck would keep runnning, but the RPMs would drop (< 500) then recover to normal idle RPM. Perhaps this is part of the 'shift-point' issues eluded to in earlier posts. I disconnected the wired plug, pulled the entire unit from the tranny - plastic teeth were fine. I reinstalled the unit, cleaned the plug terminals and all worked again. Then, last week the same problem resurfaced. Again, I pulled the unit, plastic teeth ok, this time I sperated the sensor from the drive unit to access the shaft. Everything was fine, shaft spins, no sheared pin - square on sensor side end keyed on drive side. After re-install still not working and exhibiting the stalling ill effect. Is the concensous that the sensor is shot? Perhaps I need to check voltage per FSM, but I'm not sure how to spin it (put the shaft in a drill with the sensor attached on the other end?

What OEM Part Number did you buy for the 94?

Thx - Lou M.

 

[Brentbba]

What OEM Part Number did you buy for the 94?

Thx - Lou M.

I called CDAN! Seriously - part number is at home on the invoice. If you need it let me know.

 

[landtank]

So....I swapped in new speedo sensor. However....speedometer still erratic and bouncing up over 100MPH at speeds over 40MPH. But I went on two trips today each over 45 minutes. After about 30 minutes of driving speedo seems to settle in where it should be.

Thoughts?

Perhaps an exorcism?

I would use the jumper to take the yellow box out of the circuit just to rule that out.

The first run of "truespeeds" did the same thing as I had gotten one.

It might be something with the V5 unit you got.

But I remember you saying to your friend you saw that before the install.

 

[Brentbba]

Sensor part number 83181-20040.
Sleeve Sub Assembly to the tcase 33404-22010. Replaced this part as that black piece in my pic is 'supposed' to be pressed into it and Dan noticed that and recommended replacing this as well. Less than $20 mud price for this part.

 

[gifu]

Searching on Speedo problems led me here.
1994 80 with 180K miles or so.
Speedo stopped working. But it occasionally comes back for 10 minutes or so.
Checked all connections, tested the Vehicle Speed Sensor, tested continuity all the way back to the speedo... and it all checks out.
Pulled the cluster.
Pulled speedo off the cluster... found the back of it (circuit board) burned. Look at the upper area (old speedo on Right).

Weird thing: wrecking yard that I got another speedo from had the same burn marks (harder to see, on left). going back tomorrow to find another one.

 

[Kernal]

Is it a burned board component or burned tracing? Can you post up a couple of close up photos of what actually burned?

 

[Brentbba]

Have you pulled the speedo sensor off the transfer case to see if it's ok? Interesting that both have similar burn marks. What is that side of the board close too?

 

[80t0ylc]

Is it a burned board component or burned tracing? Can you post up a couple of close up photos of what actually burned?

Looks to me like the trace on the old board is burned away and 2 pads and solder joints are gone. But you're right - need a close up with good resolution to assess damage. If new one has similar but not as bad damage, it would be interesting to find out what is going on.

 

[gifu]

to be clear, the new one had the damage before I installed it.
Tested the VSS sendor, and it tests out as per the manual.

 

[gifu]

Second used replacement was checked before leaving wrecker. Good condition. Now speedo works, check engine is off, cruise control works.

For this doing research, everything I could find said that the VSS sends signal to cluster, the cluster sends signal to both ECM and CC computer.

 

[Bigduke6]

I have the same problem. Weird shifting, occasional low idle and no speedo or odo. Replaced the vss, hoping that a lot of money and a little work would fix it. No bueno. Ordered a used gauge cluster and pulled apart, burned in the same spot as yours Gifu. Haven't gotten the dash apart(upper trim by the clock must have a fastener I can't find). Since I have 2 I think I will try to repair connectivity on the wrecking yard one and see if I can get it working that way. Thanks, Gifu, your pics really helped me. Maybe this should be faq'd?

 

[Bigduke6]

got mine out of the dash, same marks as the others. that makes both of the ones i have in hand, plus the two that Gifu had. This seems like it is a common failure. would be nice to know the cause. does anybody have a pic of a good board so i can try to repair this? can't really tell what went where given the current condition. this sucks. Thanks for any help.

 

[Bigduke6]

Well, jumped across the burned traces with some phone wire and solder and reinstalled,speedo works! Still may not be getting signal to ECU (OD light flashing)gained over 200,000 trouble free miles though. Mine had 184k, new odo has 287k. More Later.