So one day I was out, enjoying the breeze with the T-Tops off... I had exited the highway, parked at my destination and boom a straight buzzkill... My speedo / odometer just quit working. I happened to notice it was stuck on like 70MPH.

92 RS w/ 305 TBI

Can anyone direct me down the troubleshooting path? Is this electronically controlled? Where should I start?

 

Sounds like the issue is in the instrument panel. Next to the ecm is a Vss buffer box. This is a yellow box that receives the vss signal then converts the signal and sends it along to the cruise control and speedometer. I would disconnect the buffer and if the speedometer is still stuck at 70 it would be a bad instrument panel.

 

On second thought, if the speedometer is stuck at 70 and your not driving key off the issue has to be in the instrument panel.

 

Yes, It's frozen at about 70MPH while parked, car off, key removed. Can only that section of the instrument panel go bad? The RPM's work, SES Light, AirBag Light, etc all work...

 

Yes, just the speedo can bad. You might want to post in the classifieds for a used cluster. If your tach works fine you might need to transfer over your tach board. They are known to go bad and read high.

 

While it could be worse... this sucks. I was all ready to jet home after work and disconnect the yellow VSS Buffer box to test the theory but now it looks like I'll be searching for a replacement instrument panel, unless the speedo has a control board that can be purchased / swapped. No matter what the solution, can one adjust the mileage? I put about 1K miles on it after the speedo quit and I'd like the counter to be as close to accurate as possible lol!

 

I just pulled the printed circuit board out of my '88. It is de-laminating in lots of places, and has lots of verdris on it even in places where it isn't alread torn or cracked.

You might want to take a close look at your printed circuit, and see if there is anything obvious. It is possible to repair damage to a printed circuit if you are handy.

Otherwise, the last one for your model-year can be had for $70 at https://www.wc-autoparts.com/1990-92...9823-25089464/

 

If you need the actual speedometer or other gauges, you can get those too from that same website.

If you want a used part, good chance you can get one from Jason at Third Gen Salvage.
See https://www.thirdgensalvage.com/

I usually reach Jason by FaceBook Messenger. He is very responsive, and his prices are extremely reasonable, and very fast shipping. But remember, Jason's stuff is USED parts.

 

If you do not want to repair it yourself, there are several speedo/instrument shops which can repair your cluster.

There is a very good chance it is mechanically bound, and may require springs or simply lubrication. It would be a good time to proactively service the tach so it reads properly.

https://www.thirdgen.org/forums/elec...meter-fix.html

 

I don’t know the price but hawks has the ip
http://www.hawksmotorsports.com/cama...gauge-cluster/
You might check eBay too a good price for a cluster is 1-$150 .
https://m.ebay.com/itm/90-92-CHEVROL...EAAOSwt5Va-hUN

It’s for a v6 so you could always swap over the tach and faceplate says it’s foggy.

 

So I've come across two things...

1. I do not have a "Yellow" box mounted anywhere near the ecm, however there is a small black one... unless I'm looking in the wrong area.

2. I picked up my NOT so trusty Haynes and it must have been based on the complete tear-down of a pre 90-92. What is the correct removal procedure for the instrument cluster? This sliding headlight **** going through the bezel is holding me up...

Any assistance would be appreciated

 

There is a button on the headlight switch that needs to be pressed to release the headlight switch rod. I can’t recall where the second area that the vss buffer is.
Post 67 shows it
https://www.thirdgen.org/forums/elec...-camaro-2.html

It can’t produce a signal with the car not moving so I think the issues in the ip.

 

UPDATE:

Lowered steering column, *removed trim, removed gauge cluster. Cleaned contacts on the cluster side and the wire harness side in the dash. I did find a little yellow box while looking for the release pin for the headlight ****, unplugged it. Reassembled, reconnected battery, started engine. No action on the spedo, still pegged at 70mph. Is there anywhere I should be checking for voltage? Was the yellow box I found even the VSS Buffer Box?

* I also cannot get the *#%$& headlight switch back into position. It goes about 95.5%, and I have the release button depressed. Now I have no headlights :-(

 

The headlight button needs to be rotated as it is inserted to align with the dimmer switch rheostat. It can then be pushed into place and latch onto the locking button on the side of the switch. It may help to lightly coat the end of the switch with white lithium grease.

 

They need a video for the headlamp ****, now i have to have her home before dark. It's not going in rotating or not or I do not have the special touch, it's beyond a pita. All it took to remove it was a spring loaded pin be pressed. Haynes says installation is reverse of removal... I beg to differ. I need help with this now in addition to a new instrument panel.

 

I AM able to get the SOB in and seated completely and lights work... ONLY if that trim is removed. When I put my dash trim back it all goes to hell!

 

That's weird, whenever I had the rod and **** out I just stuck it back in and it clicked right in place no problem??
Did you ever get your cluster problem fixed? I have a couple of spares. I always test out in my car before selling one to anybody Just LMK
Good luck,
Henry

 

I finally got it back in, I looked in the hole and found it's not a straight in shot as in my unit it's not level. I applied a little upward pressure pushing the shaft down and click it went back in. I did not get the cluster going and found a guy locally claiming they're selling one for $50 but stated it's in storage and they aren't responding in a timely fashion. What are you asking for your cluster? It would be shipped to 43227.

 

I've got three of them I think
and not sure I remember which one I tested before. I assume you would rather get one tested good. it's like 106 degrees out there right now so maybe earlier tomorrow ??
Henry

 

Tomorrow sounds fine.

Thanks.

 

Hi, had some stuff to deal with earlier but getting to the testing now. Get me your email address for pics and other info
Thanks, Henry

 

ewitcher06@gmail.com

 

I think I can help a bit here. My 3rd gen is actually my '89 K1500 with a 350 and 700R4. I've rebuilt/ reconditioned everything on this truck and a lot of systems are very similar to the F-bodies. My Mom's old car was an '87 Firebird that I learned a lot of tricks on along with my '69 and '98 Firebirds.
The speedo in my '89 truck quits working intermittently and what you may not realize is that the speedo is tied in with the ECM. I'll be driving down the road paying attention to the highway and suddenly I hear my engine change tone and all of a sudden the speedo drops to 0 and if I wait too long I get a CEL. I've had the cluster out and replaced the individual speedo gauge with a NOS part I bought. I've traced the circuit path on the circuit board of the cluster and re-soldered possible open joints. (I replaced the VSS sensor and no change in my case also.) I didn't seem to find them. What's my fix? For now I give the gauge cluster a good, "Fonzie whack" and it starts working. It's mainly more of a problem when it's cold in my situation. I have a spare cluster that I'll try eventually.
Now you didn't mention whether you got a CEL, but I imagine if the speedo went open like mine does you would get one; CEL, that is. I would bet that the speedo gauge itself is bad and I would replace that unit if I were you after reading all the actions take so far.

 

*UPDATE*

Picked up a Instrument/Gauge Cluster from a local yard today w/ 30 day warranty for $35. I'll be swapping clusters after work and will post the outcome at that time..

@ 6998poncho - No CEL related to speedo operation. Last time I tried soldering something it didn't go so well and that was in the Laptop PC world so there's no way I'm trying that with my cluster. Now LOL in the event the unit I pulled today is operational then I'll consider taking a shot at repairing the original. Thanks for sharing your story and what worked for you though!

 

*Update*

I found it amazing the things people will do to avoid doing the right thing... So the 1990 RS w/ L03 TBI & 700R4 had a manual gauge cluster this sucks. While yes the speedo works, because it for a manual the ENTIRE right side (RPM's Voltage, etc) doesn't work... I totally didn't see the very faint shift indicator as I was pulling it.

So I'll be swapping back to my original & that leaves me with a 1228746 ECM/PROM for a manual and now a working cluster for a manual just sitting around.

*** I've found that the shift indicator is on both auto & manual, it's just that auto doesn't have the bulb in the space so someone like myself would be easily confused!

 

I've gotten 90-92 clusters out of auto and manual cars that work fine in my 5speed car . I didn't think there was a difference in the
clusters at all? The tach works off of the distributor pulses so it shouldn't care what trans it has

 

Interesting.

 

Yeah, I think for those years all that matters is that you match V8 and V6 clusters with those cars. I had a 145 speedo one that worked perfectly in my 5.0 TBI 5speed car and it was from an automatic although I don't have an auto trans car to test with. Every person I sold one I tested in my car to said they worked perfect whether it was auto or 5speed. So I only assumed it didn't matter from past experience and not from actual factual data...
If the speedo works you should be able to swap it over into your cluster I would think

 

Can you take the face off the gauge cluster and swap individual speedo guages. I might try that. There's usually some 7mm hex headed screws that retain the gauges in the plastic pod. People have made You tube videos on this stuff.

 

*RESOLVED*

So knowing I had the following three clusters... I've found a solution!

1. Original In-Car - All gauges work EXCEPT Speedo
2. JY Pull from 90RS - Speedo works Tach, Temp, Voltage, and maybe Oil Pressure didn't
3. Used unit purchased on Letgo - All gauges work EXCEPT Speedo, return/refund unavailable

While doing a little research I found that a PCB board is in place on both sides, both of which fail. Pulled cluster 1, Swapped in the tach side PCB of Cluster 3 which was known working into Cluster 2. Swapped in cluster 2 to replace Cluster 1. Put everything back together and within 15ft of exiting the driveway I saw the speedo operational as well as all other gauges!

 

Cool, isn't it fun to learn new stuff when it ends up fixing what you were trying to do!
Nice one

 

I know this is WAY late, but I'm going to send my cluster (when I get the headlight switch arm out) with no working gauges, to United Radio to get fixed. I found out about them from LSX_Matt on YouTube.