Cluster Swap

[Finn]

Hello currently I have a 1990 gmc C1500 I have a moonie cluster which works except the speedometer which doenst read whatsoever I currently acquired a 1990 Chevy C1500 cluster with also the moonie variant. I wanted to know if I just switch them out would it be plug and play since they’re the same year and same variant of would I have to do other things to make it work?

 

[someotherguy]

1990 for 1990 are direct swaps - BUT - the speedometer calibration is done inside the cluster on 1988-1991, so if the donor truck came from factory with a different tire size (height) or rear axle ratio, it will not read correctly on your truck. If the SPID label (option label inside glovebox) is still legible, long shot, you can compare the RPO codes. The axle ratio will be the most probable one to be different, look for codes starting with G.

I'd check into why your speedo isn't working, first. Most likely suspect is the speed sensor in the transmission.

The 1988-1991 cluster design does suffer a little bit from bad solder joints/connections inside causing the speedo to go intermittent or fail. I've seen a few people bust up their dashboards beating on them to make the cluster work again for a while.

You can recalibrate your replacement speedo using the factory "programming clip" kit which can be hard to find, or you can use a multimeter to check how your current one and donor one are set and solder in jumpers to match if needed, or easiest way is to solder in a DIP switch and make it permanently configurable as needed.

My wonderful POS web host (godaddy) not having "secure" http unless I give them lots of $ is why the pic links are broken -> https://www.chevytalk.org/fusionbb/showtopic.php?tid/258562 - you can either accept "insecure" content from that site, or you can right-click and open them in another tab to see. I detail installing a DIP switch in the cluster so you can calibrate as needed.

Richard

 

[DerekTheGreat]

In addition to what SoG said, check the fuse which supplies power to the speed sensor. It's a 15 amp, forget which but that ended up being the problem with my old '88. Well, the fuse wasn't bad but the socket was all corroded. I found that out after I fired the parts cannon and bought a speed sensor, of course.

 

[Ilija Kovacevic]

In addition to what SoG said, check the fuse which supplies power to the speed sensor. It's a 15 amp, forget which but that ended up being the problem with my old '88. Well, the fuse wasn't bad but the socket was all corroded. I found that out after I fired the parts cannon and bought a speed sensor, of course.

Where would the fuse be located for that?

 

[DerekTheGreat]

If you pull the cover that's to the right parking brake release handle, it'll be labeled "Brake." Second row from the top, second column from the left. Should be a 15 Amp'r.