How to Fix Capri Fuel and Temperature Gauges
If your Capri fuel and temperature gauges are a bit random then your voltage regulator is probably at fault. This is a small and cheap part located in a module on the back of your dash pod, just behind the Rev Counter.
You need to replace the 7805 voltage regulator. These can be bought cheaply from Maplin, off ebay or a local electronic components shop. They are typically less than a pound each.
What will I need ?
- A new 7805 voltage regulator (maplin)
- A tube of heatsink compound (maplin)
- A screwdriver
- A soldering iron
- Some solder
- A large drill
- A rivet gun and a rivet
How long will it take?
About 1 hour: About half an hour to remove the module and fix it, prpbably another half an hour to extract and re-fit the dash pod.
What does the voltage regulator do?
It converts a variable voltage from your 12V circuit (say 11V to 14.5V) and converts it to a stable and rock solid 5V. The gauges use this 5V as a reference voltage so it needs to be steady. The reading on your gauge is effectively a reading compared to this 5V reference.
Step 1: Remove the dash pod from your capri.
Step 2: Locate the voltage regulator module on the back of the dash pod.
Step 3: Unscrew the single screw holding the module to the dash pod and remove the whole module.
Here's the module (right) with a new 7805 (left) ready to go in.
Step 4: The 7805 voltage regulator (square black compenent with 3 legs) is rivetted to the heatsink (metal square thing on the top) and the circuit board via one rivet. Drill this out (very carefully : do NOT enlarge the hole : use a big drill and just take the face off the rivet - it's alloy so is easy to drill).
Step 5: Separate the heatsink from the module. Now unsolder the 2 legs of the 7805 (the middle leg isn't connected)
Note: the middle leg on the 7805 is earth, so is the metal tab. The metal tab is rivetted onto the heatsink and the circuit board thus providing the earth connection.
Step 6: You'll be wanting a new 7805 and some heat sink compound (Maplin will have both). Smear heatsink compound on the back of the 7805 (the metal area - but not the legs).
Step 7: Solder on the new 7805 (only the outer 2 legs need to be soldered on: you can cut the middle leg short).
Step 8: Rivet the heatsink back on : the rivet should go through the metal tab hole of the 7805 and the heatsink and the circuit board.
Step 9: Re-fit to the back of the dash (single screw)
Step 10: Re-fit the dash pod to your capri.
All done: your temperature and fuel guages should now be more accurate and not random.