fog lights wont work!

cre · 10-11-2009, 03:17 AM

Wiring diagram: http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=076

That diagram is for a later model, as you've noticed, the wiring colors vary, but the routing is the same.

In stock form, the fog lights are are routed through the headlight switch (has it's own contacts, so a damaged switch is possible) thus requiring the headlights to be turned on for the fogs to light; the fog light switch; and the fog light relay.

If you do find that the relay is closing when the aforementioned requirements are met, but still no fogs, test for voltage at the foglight housings... it could be bad bulbs or grounds.

And it's not an ohm meter... an ohm is a measure of resistance and in this case such measurements would do you no good.

For this you'd be using a volt meter or (more likely) a multi-meter (rather commonly referred to as a DMM - Digital Multi-Meter).

Also, be careful with the stock relays, they're not always interchangeable and you could damage something you don't want to pay to replace. They're not like Bosch relays which are pretty much standardized (except for a few uncommon types).

10-11-2009, 03:17 AM	#9
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Wiring diagram: http://www.cygnusx1.net/Supra/Librar...x?S=Main&P=076 That diagram is for a later model, as you've noticed, the wiring colors vary, but the routing is the same. In stock form, the fog lights are are routed through the headlight switch (has it's own contacts, so a damaged switch is possible) thus requiring the headlights to be turned on for the fogs to light; the fog light switch; and the fog light relay. If you do find that the relay is closing when the aforementioned requirements are met, but still no fogs, test for voltage at the foglight housings... it could be bad bulbs or grounds. And it's not an ohm meter... an ohm is a measure of resistance and in this case such measurements would do you no good. For this you'd be using a volt meter or (more likely) a multi-meter (rather commonly referred to as a DMM - Digital Multi-Meter). Also, be careful with the stock relays, they're not always interchangeable and you could damage something you don't want to pay to replace. They're not like Bosch relays which are pretty much standardized (except for a few uncommon types).