# Segment 5 9/6/2014 ignition time delay relay

**URL:** <https://community.cartalk.com/t/segment-5-9-6-2014-ignition-time-delay-relay/87058>\
**Category:** The Show\
**Created:** [September 7, 2014, 7:30pm UTC](https://community.cartalk.com/t/segment-5-9-6-2014-ignition-time-delay-relay/87058 "2014-09-07T19:30:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![thebordercolliefixes](https://avatars.discourse-cdn.com/v4/letter/t/ea5d25/32.png) [@thebordercolliefixes](https://community.cartalk.com/u/thebordercolliefixes)\
**Post date:** [September 7, 2014, 7:30pm UTC](https://community.cartalk.com/t/segment-5-9-6-2014-ignition-time-delay-relay/87058/1 "2014-09-07T19:30:40Z")

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Ignition time delay relay…nothing to do with the coil. At all.

It keeps the ignition switch light illuminated for a little while after  
you shut the door, so you can see to insert the key at night. It works on  
a very simple principle: There’s a resistance wire wrapped around a  
bimetallic strip. At the end of this bimetallic strip is a contact, which  
when the strip is cold touches another contact located on a plain metal  
support. When the door is opened, the interior light circuit is energized  
by the door switch. The dome, courtesy and ignition switch lights come on.  
Current also begins flowing through that resistance wire, which heats up  
the bimetallic strip. When it reaches a certain temperature, it flexes,  
moving the one contact away from the other and breaking the circuit to the  
ignition switch light.

If your car has one of these and you want to isolate it by feel, leave your door open and the dome light on for a few minutes and grab the relay you believe to be the “ignition time delay relay”. It will be toasty warm, or damn hot even.

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**Author:** ![George\_San\_Jose1](https://avatars.discourse-cdn.com/v4/letter/g/e5b9ba/32.png) [@George\_San\_Jose1](https://community.cartalk.com/u/George_San_Jose1)\
**Post date:** [September 8, 2014, 4:36am UTC](https://community.cartalk.com/t/segment-5-9-6-2014-ignition-time-delay-relay/87058/2 "2014-09-08T04:36:01Z")

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But if it is only for lighting, why – if it was malfunctioning – would it prevent the engine from starting?