Problems with gauge cluster in 89

[geeeee89]

Just bought an 89 C3500 last week.

The odometer and tripometer both don't work. The speedometer only works occasionally.

All the other gauges - oil pressure, temp, voltage, and fuel - all work fine and seem to be accurate.


What could be the cause of the odometer not working and the speedo only working sometimes? Is this likely to be a bad gauge cluster? Bad wiring/ground? Bad speed sensor?

What specifically controls the odometer that I could check?

 

[PlayingWithTBI]

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.

 

[geeeee89]

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.

Thanks, I've been reading through some of his stuff. The dakota digital gauges are nice but I'm going to try to get mine fixed or buy a junkyard/ebay replacement first.

When replacing one from the same 88-91 range, does it matter if the donor truck has the same engine? I don't think finding a gauge cluster for a 454 truck with a non-overdrive trans will be easy, but clusters from a truck with a 350 and overdrive are pretty common. Would anything get wonky if I put one of those in mine?

 

[PlayingWithTBI]

I don't think finding a gauge cluster for a 454 truck with a non-overdrive trans will be easy

Maybe yes maybe no. I thought all 454s came with a 3 speed since the 700R4 couldn't handle the torque. Even the 454SS came with a TH400 trans. The only difference would be if you had a tach and you swapped a 6 cylinder dash into your V8 truck. Your gear shift indicator might come into play but IIRC that's separate and underneath the cluster?

 

[evilunclegrimace]

There are a few of them out there. My '88 K3500 had a 5.7 and a THM 400 and I am willing to bet that it would work in a 7.4.There were also plenty of 7.4 2 WD trucks made

 

[PlayingWithTBI]

My '88 K3500 had a 5.7 and a THM 400

I forgot about that, all 1 Ton trucks came with the 3 speed trans huh?

 

[geeeee89]

Hmm I guess that’s true, I don’t have a tach and don’t really care about having one. Just want operable gauges. Doesn’t matter about the shift indicator either, mine doesn’t work anyway. I guess that opens up some more options

 

[evilunclegrimace]

I forgot about that, all 1 Ton trucks came with the 3 speed trans huh?

I can not say 100% that all 1 ton trucks came with 3 speeds but, I saw plenty that did roll out of the dealership that I worked at. The Railroad, Electric Company and local govt. bought most of them and most had utility bodies on them. Some of the smaller govts. had fleet sides with SM 465 tranys

 

[DerekTheGreat]

Pretty sure none of the one tons had OD until about '91.

Anyway, I'd just try cleaning up the pins and other contacts in your cluster since you said the problem is intermittent. You could also just try scouring a "treasure yard" for another one, swap that in and see if it works just fine. That'll help narrow down where the problem is if nothing else. Careful though, the cluster's speedometer is internally calibrated. So for spare parts and testing purposes you can purchase any cluster but if you're looking for a painless drop in replacement, pay attention to the wheel size and rear gear of the donor vehicle..

 

[geeeee89]

Pretty sure none of the one tons had OD until about '91.

Anyway, I'd just try cleaning up the pins and other contacts in your cluster since you said the problem is intermittent. You could also just try scouring a "treasure yard" for another one, swap that in and see if it works just fine. That'll help narrow down where the problem is if nothing else. Careful though, the cluster's speedometer is internally calibrated. So for spare parts and testing purposes you can purchase any cluster but if you're looking for a painless drop in replacement, pay attention to the wheel size and rear gear of the donor vehicle..

great, thank you. if the clusters will work from any 1500-3500 in that year range, i'll just find a nice working one and if i have to recalibrate it there's a process someone posted on here that I could do. I don't mind if it's a little off, i'm used to that with my 97 model.