Problems with gauge cluster in 89

Yep, any GMT400 truck will do, 1988 to 1990

There is a write up on it. The external recalibration kits are long gone but you can re do the board yourself IIRC. You can also convert your stupid moonie dash like I did to the later needle style & net yourself a tach in the process. You need the special 1990.5 cluster (swaps in directly) though, and those are hard to come by and pretty expensive on the interwebs. I've done this to both our pre 1990 trucks that we had. I drive a stick so it's a must for me, also a great diagnostic tool for the ignition system as once that ICM goes wonky or there is an issue somewhere else it usually makes the signal buggy so you have a heads up.

Here's a thread on calibrating your speedo. You can also solder in dip switches instead of jumpers.

http://67-72chevytrucks.com/vboard/showthread.php?t=313815

The odometer in my '89 wasn't working because the gear was cracked. It's driven by a little electric motor, that from what I've read, rarely is the problem. When I tore it apart I couldn't figure out the problem at first, the drive gear crack wasn't noticeable and it was only half of the gear that cracked. Had to hold it just right to see the crack. Took awhile but I finally got lucky and found an amazon warehouse one for a decent price.

https://www.dormanproducts.com/p-73...0&parttype=Odometer%20Drive%20Gear&origin=YMM

A couple Pics

Thousands of years ago, I had an instrument panel fault--intermittent--that would disable the speedo,odometer, trip odometer, cruise control, and ABS on my '88 K1500. Sometimes I could smack the instrument panel with my fist and everything would work again.

Of course I replaced the speed sensor in the transfer case. Of course, that didn't help.

I got a Treasure Yard instrument cluster, replaced my speedo with the one from the Yard. No difference. Eventually put the speedo back into the Yard instrument cluster, and put the whole cluster in my vehicle--bingo. Worked great for ~10 years, maybe.

Now my Odo and Trip Odo don't work again, but no effect on speedo, cruise, ABS. Probably the gears that drive 'em.

I had the same gear crack on my '90 GMC and was equally hard to spot. The left side odometer drive gear is available, as you found out, but the right side gear that moves the trip odo is impossible to find (it's also a different gear). You'll know when the trip odo gear is cracked because it will jam or shove the digits to the left and all four will start rotating at the same time. My trip gear was fixable with a bit of epoxy and reaming out the center hole with a small drill bit. GM didn't put any sort of key on the shafts for either gear so they have to be tight to avoid slipping - probably why they crack in the first place.

got a cluster from a junkyard this weekend and it works in mine just fine. Speedo is off and odometer rolls way too fast, but the new one came from a 1500 with probably 3.42 gears

PlayingWithTBI said:

Mine did that too it started with the main odometer quit, then the trip odometer. A couple years later the gas gauge wouldn't go over 1/4 when full. Then the temp gauge quit. That's when I started searching for a replacement. At the time the Dakota Digital dash was cheaper than a reconditioned one.

These older GMT400s (88-91) have an adapter, similar to the newer DRAC or VSSB, on the back of the cluster which converts the 2000 PPM (Pulses Per Mile), from the VSS (Vehicle Speed Sensor) and feeds the speedometer and the ECM. Anyway, you may have a bad ground or solder joints on the PCB.

@someotherguy has done some write-ups on these.

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Good morning. Do you have any images of the Adapter similar to the newer DRAC or VSSB? I have a 1990 K1500 5.7L Silverado. Been troubleshooting the speedo for weeks.

Seosamh said:

Do you have any images of the Adapter similar to the newer DRAC or VSSB?

Click to expand...

No, I threw the cluster away about 8 - 10 years ago. Maybe someone else has one.