minor mod: a pair of idiot lights

[HafNHaf]

hi gang! well, i finally got a chance to do a minor mod i have been thinking of for a while. i put in a pair of LEDs that show the status of two relays under the hood: the a/c compressor relay, and the fuel cut relay. i ran a twisted, shielded pair of wires from the area near the 2 under-hood fuse/relay boxes on the driver's side of the engine compartment, around the left side fender, and into the passenger compartment. each wire of the pair was soldered to an LED (blue for a/c, and green for fuel cut). then each LED has a dropping resistor soldered on, and then the resistors go to a single ground lead, which gets grounded to a bolt on the hood release handle bracket by the left-side door.

the blue LED comes on whenever the a/c relay supplies voltage to the compressor. that way i can see when it cycles, but mostly i can remember to turn the damn thing off if i have been running it only on the down hills.

the green LED comes on whenever the fuel cut relay is supplying voltage to the fuel pump. that way i can make a better-informed desision whether to let the wheels drive the engine and regen the battery, or do a FAS. i will however be putting in a relay to make the LED go ON when the fuel cut relay is OFF. more in line with the autostop LED on the dash.

knowledge is power! or at least it can lead to higher MPGs. i hope!

pics and wiring info to follow.

[HafNHaf]

a mod for the mod: instead of a green LED for fuel-cut (or fuel-in-use, depending on how it's wired), use a bi-color LED and a DPDT relay. orange for fuel-in-use, green for fuel-cut. thats how mine will be by the weekend.

[Insightful Trekker]

Eagerly awaiting the schematics

[HafNHaf]

ok, here is the diagram. i dont remember offhand which terminal of the fuel cut relay i picked up the power from, but it is easy enough to figure it out with the relay out of its socket. with the ignition key on, it is the socket that does NOT have voltage on it that goes to one of the two copper tabs on the relay. that is the output of the relay. the one with voltage on it that goes to the other copper tab is the input, and the two sockets that go to the silver tabs are for the relay coil.

i will try to get a pic of the relay socket tomorrow.

[dloop]

How about a photo of how you mounted them idiot lights?

[HafNHaf]

so far the 2 LEDs are just sticking up from the gap in front of the instrument panel. not very elegant, but i have not had time to dig into the dash and mount them properly.