Fuel Gauge

From Holdenpaedia
Jump to: navigation, search

Page created by T Sunday July 15th 2012:

Back to Electrical Index

Pic 1. HZ Fuel and Temperature Gauge. Photo by Onlyholden. Click to Enlargen.

Fuel Gauge:

HR Fuel Gauge Repair:

66hrute successfully repaired the Fuel Gauge in an HR by replacing the burned out 12 ohm 5% resistor inside it.

HZ Fuel Gauge:

THe HZ Holden Fuel Gauge is powered by a Thermal Voltage Regulator.

Thermal Voltage Regulator:

The ex-factory Voltage Regulator is a thermal device meaning that it is operated by temperature. When the device is cold its 2 contacts are closed, providing current to the Gauges. The device is heated by a winding of wire. When the wire reaches temperature the contacts open, preventing current from reaching both the Fuel and Temp Gauges. This action keeps the Gauges from over or under-reading.The thermal Gauges are so slow to operate that the on off action of the Thermal Boltage Regulator is not shown on the Gauges.

Solid State Regulator:

All Holdens after HZ used a Solid State Regulator, such as the 7805 Integrated Circuit. It is advisable to convert to  the Solid State Regulator for improved reliability if any work is being done on the Gauges. The Solid State Regulator has internal thermal and overload protection making it ideal for use in OH dash boards.

The Fuel And Temperature Gauges Stop Working:

If this happens the cause is highly likely to be a failure of the Voltage Regulator. Steps for converting to a Solid State Regulator are below.

Steps For Converting To A Solid State Regulator:

1. Disable the Thermal Voltage Regulator by bending the contact up and cutting its wire (Pic 4).

2. Install the 7805 as shown (Pic 5, Pic 6, Pic 7 and Pic 8 ). Use 2 amp hookup Wire. The black sheath is called heat shrink and can be shrunk into a tight fit by blowing it with a hairdryer.  

 
Pic 2. HZ Fuel and Temperature Gauge. The factory supplied thermal regulator is in view. Photo by Onlyholden. Click to Enlargen.
 
Pic 3. The contacts of the Thermal Voltage Regulator of the HZ Fuel and Temperature Gauge are visible on the lower left hand side of the photo. Photo by Onlyholden. Click to Enlargen.
Pic 4. HZ Fuel and Temperature Gauge with 7805 Regulator fitted. Photo by GraemeG. Click to Enlargen.
Pic 5. The rear of the upside down HZ Fuel and Temperature Gauge. The black plastic devices hold the illumination bulbs. Rotate these 90 deg anti-clockwise and then pull them out but only if you wish to service the bulbs. Photo by Onlyholden. Click to Enlargen.
  
Pic 6. Shows where the 7805 +5 Volt Regulator is to be fitted (shown lower left).   Photo by GraemeG. Click to Enlargen.
 
Pic 7. The Gauge is no longer upside down. This view shows the 7805 fitted to the Gauge. The uppermost connection is +12v in. The centre connection is ground (earth). The lowermost connection is + 5V out. Photo by Onlyholden. Click to Enlargen.
Pic 8. Make the conections between the 7805 and the Gauge.  Photo by Onlyholden. Click to Enlargen.
Failed 12 ohm resistor and its new replacement for an HR Fuel Gauge. Photo by 66hrute. Click to Enlargen.
Replacement 12 ohm 1 Watt 5% resistor used in the HR Fuel Gauge repair. Photo by 66hrute. Click to Enlargen.

 

Heatsink:

It is advisable to fit a heatsink   to the 7805 regulator to help it stay cool.

Links:

HZ Temp Repair Link 1

HZ Temp Repair Link 2

HZ Temp Repair Link 3

HZ Temp Repair Link 4

HZ Temp Repair Link 5

7805 5 Volt Voltage Regulator

7805 From Jaycar ]

HR Fuel Gauge Repair

HR Fuel Gauge Resistor Details

Terms:

Terms

Back to Electrical Index