Install a P-Body Gauge Cluster in a K-Body

Quite a while ago, I got the bright idea to convert over my entire gauge cluster into something newer, but the project never got off the ground because its a lot of work and I can tend to be lazy with projects if I don't necessarily need to get them done anytime soon. More recently however, I decided that instead of replacing all the gauges, I would just find a way to print up my own faces and apply them over the old faces and what tests I did ended up working really well except when it came to lighting the gauges. The K-Body cars never had backlit gauges, only frontlit and while frontlit works great for simpler designs, it ends up being poor for many other designs.

Then it happened, my speedometer began to swing widly when below 25mph; my speedometer cable was finally going out. I managed to help alleviate but not solve the problem by filling the old cable with lightweight oil but I had already decided, I was going to switch over to a new cluster with an electric speedometer.

Decisions, decisions, what other K-Cars share newer but similar clusters. My answer came in the form of a new car purchased for a family member, a P-Body. The P-Body has a gauge cluster that not only shares connectors with the K-Body cars but the gauges are the same sizes and share all the same connections. Moving the gauges from one car to the other would require only retracing the PCB board and a single splice for the speedometer signal, and relatively minimal modification of the actual cluster.

There are four available P-Body clusters, mechanical speedo w/or w/out tach, and electric speedo w/or w/out tach. For the sake of minimal work while still getting rid of the speedometer cable, I decided on the electric speedo w/out tach model as it is the closest to the original K-Body cluster. After this project has been completed with this cluster, I'm going to do the entire project over again only using the electric speedo w/tach; I already have a tachometer installed on my dashboard and would actually like to get rid of it and replace it with an in-dash tach.

There are actually two style gauge clusters that came in K-Body cars, they are physically the same except the connectors changed at one point. The new style clusters have two cylindrical connectors while the old style clusters had one cylindrical connector and one linear connector. I have gone ahead and made a diagram for both, as I have the old style cluster but plan on modifying the harness to the new style as the cylindrical connectors are easier to remove and replace. I have also made a diagram for the P-Body cluster so I know exactly how to wire in the new gauges.

Despite sharing the same connections as the K-Body gauges, the P-Body gauges are different in that the fuel/voltage/temp is all one gauge in the K-Body cars while they are all seperate gauges in the P-Body cars. This actually does not complicate the wiring at all but it does make for the need to redesign the gauge cluster. So I've come up with an early concept of how I would like the lay out the gauge cluster; at this stage I'm just arranging things so they fit and look good while doing it but the design will most likely change before all is said and done.

This is also the stage where I can add whatever zany idea I want, regardless of how much complication it would add to the project because I can always just drop it without doing any actual work on it. If you'll notice S1 in the concept below, you'll see that it's labeled [Shifter Position] and the idea is just as it sounds, to display the shifter position (not necessarily the gear) on an in-cluster LCD.

The concept is actually simple in theory, place either pressure switches or contacts down where the shifter will activate them and have the switches change the LCD display. This concept can actually be taken a step further and display the actual gear the car is in, as even despite the lack of a sensor on the transmission to read from, a simple calculation (rpm / mph) and check against a value table will give you the needed value. Its a simple calculation but even that adds an entire level of complication, requiring a chip (~4mhz) and ROM (~64byte) to compute the gear, instead of just physical traces in the case of just showing the shifter position. Like I said, this is the stage I get to throw around crazy ideas.

For the other labeled sections on the concept below, they're all pretty self explanatory and the blue areas mark the regions they would approximately take up.

If you have any comments, suggestions or questions, just throw an email my way: Justin Brimm.

Return to Projects | Return to Main Page
Copyright © Brimm Motorsports