Operating instructions

4.8.3 Timer and Switch Connections
1. Select a suitable location in the vehicle dash for the timer or On/Off switch.
2. Drill a 1/2" hole through the dash for the switch or see timer dimensions.
3. Route and secure switch harness from the heater to the vehicle dashboard. If possible use
existing hole in fire wall or drill in suitable location. Protect the harness with a grommet at the fire
wall.
4. Connect the terminals to the timer, or switch. See figures 418, 419, 420, and 421 below and wiring
diagram figure 423 for reference.
Fig. 418: On/Off Switch
Fig. 419: 72 Hour Quartz Timer with On/Off Switch
428
4 Installation Thermo 90 S
CAUTION
When drilling holes on the vehicle, do not drill into existing wiring or other mechanical components.
CAUTION
If welding is done on the vehicle, the main battery cables must be disconnected from the battery to
protect the electronic control unit.