H4 Relay's - Post Installation Question

keitho64 · keitho64's Garage

I wired up the relays for the H4's on my car per many threads here. After the installation, the battery will go dead if the car sits for a week. It did not do this before. I connected a test light between the ground wire and battery and I know I have a power draw. If I remove power from the relays, the power draw is gone. So, I either have the relays wires wrong, or maybe, there is a problem with them. I have the relay's wired as follows:

Pin 85 - Ground
Pin 86 - Trigger from the light switch
Pin 87 - Power to the lights
Pin 30 - Power from battery (always on, this is the source of the power draw)

I am using two relays, one dedicated to low beam and one dedicated to high beam. Does anyone see a problem with the relays being wired as I outlined here?

It is not a big issue because I disconnect the battery if the car sits for a while, however, I know this should not happen. And yes I know the obvious answer - drive the car every day.

Thanks

TMH · 09-17-2003, 10:46 AM

I'm not sure if it is the same relay you have used, but from what I see you might have pins 85 & 86 swapped. Check out the following, and see if it is the same relay and clears anything up for you.

http://www.classictruckshop.com/clubs/earlyburbs/projects/bosch/relay.htm

Tom

TMH · 11:06 AM

Wait a minute, I might have steered you wrong in the last post. Here is another relay installation diagram I found, which appears to be the way you already have it wired.

Tom

TMH · 09-17-2003, 11:06 AM

Here's the diagram.

keitho64 · keitho64's Garage

Tom

Thanks for the info. Based upon what I see, I have it wired correctly. I am going to try isolating one relay at a time (I disconnedted both when checking the power draw) and see if one is bad.

Early_S_Man · 09-17-2003, 12:59 PM

Keith,

From your description it doesn't sound like there is any problem with your relay wiring or installation.

However, there may be a problem with your light switch or control stalk switch that is feeding current to the #86 terminal of your relay ... causing a drain on the battery, even if the current isn't enough to operate the relay! The DIN 'icecube' relays have coils with a resistance in the 70 - 100 Ohm range, and that represents enough current from ~12 Volts to drain a battery in one or two weeks.

I suggest checking terminal #86 at both relay sockets for Voltage presence with a digital multimeter while the relay is pulled and the ignition switch is off with the key out.

keitho64 · keitho64's Garage

Warren,

Excellent idea, I never thought of that. I will look into that tonight and post my findings. Thanks!