REAR WINDOW DEFROSTER RELAY/TIMER AND UPDATE KIT

TECH NOTES:

A relay is an electrically operated switch that opens and closes under the control of another switch or electrical circuit.

Relays are used where it is necessary to control a high-power circuit with a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal.

In the case of a rear window defroster relay/timer, the defroster is activated or deactivated through this relay when the rear window defroster switch is pressed. It will also automatically deactivate when the relay's programmed timing cycle ends or the ignition switch is turned to the off position.

NOTE: Did you know that GM had a flaw in the design of the 1978-79 rear defroster system? If the defroster was on with the ignition switch in the run or accessory position and the ignition switch was then switched to the off position, the defroster would continue to operate until the programmed time cycle ended. This would reduce battery life and could potentially cause a weak battery to go dead, leaving the car and driver stranded.

It was not until the 1980 model year that this flaw was corrected. This relay/timer, along with an adapter wire (included) that runs from the defroster switch to the relay timer, will update your defroster system to 1980 model operating specs. This is the same update kit that was provided to dealers. It was not provided as a "recall" repair, but as an update kit that could be sold and installed on a customer's vehicle. As such, it was rarely purchased or installed. The adapter wire must be installed and used along with this relay/timer or the system will not operate at all.