1984-1989 Cruise Transistor Replacement

Cruise Schematic


Cluster Wiring


Cruise Transistor Replacement Instructions

Supplies you'll need for this project

  • Cruise Control Transistors - Click Here to buy.

  • Digital Multimeter to check cruise solenoid OR

  • Optional Cruise Control Solenoid (eBay)


Removing the Digital Cluster

Follow the removal instructions located here.


Disassembling the Cluster

Disassemble the cluster using the documentation here.


Replacing the Cruise Transistors

Location of Cruise Transistors


The transistors to be replaced are marked Q11 and Q14 on later boards, or Q106 and Q108 on early boards. In all cases, the cruise transistors are different from other nearby transistors. The plastic housing will either be higher than the other transistors, or the housing will have a metal tab sticking out the top.


Remove the cruise transistors using the soldering technique of your choice.


Transistors Removed


Pinout of New AND Old Transistors


Both the new and old transistors have the same pinout, as shown in the image above.


Orientation of New Cruise Transistors


Install the new transistors in the orientation shown in the photo above and solder them in place.


Reassembling the Cluster

Reassemble the cluster using the documentation located here.


Before Reinstalling The Cluster

If these transistors are blown, it was very likely caused by a shorted cruise solenoid. You can check this at the cruise solenoid, or at the cluster wiring harness connector. Pins D8 and D9 connect to the cruise vacuum valve and vent valve. If you didn't replace the cruise solenoid, be sure to check yours before reinstalling the cluster. Measure the resistance between ground and Pin D8 of the cluster harness. It should be no less than 5.1 Ohms. Repeat for pin D9. It should also be no less than 5.1 Ohms. Do not connect the cluster if either measurement is less than 5.1 Ohms - that means the solenoid is shorted and needs to be replaced!