bosch relay no output to 87a
Printed From: the12volt.com
Forum Name: Relays
Forum Discription: Relay Diagrams, SPDT Relays, SPST Relays, DPDT Relays, Latching Relays, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=136169
Printed Date: May 11, 2025 at 1:25 AM
Topic: bosch relay no output to 87a
Posted By: bhamilton
Subject: bosch relay no output to 87a
Date Posted: February 26, 2014 at 9:48 PM
Ok, so I've got a relay set up as so:
86 - switched low current +12V (Switch 2)
85 - Ground
30 - Switched high current +12V (Switch 1)
87a - Light set 1
87 - Light set 2
The way I want it to work is:
Switch 1 On, Switch 2 Off - Light set 1 on
Switch 1 On, Switch 2 On - Light set 2 on
Switch 1 Off - all lights off
From what I've read, I've got it wired correctly, but what is actually happening is:
Switch 1 On, Switch 2 Off - No lights on, no voltage out of 87a
Switch 1 On, Switch 2 On - Light set 2 on
Switch 1 Off - all lights off.
For the life of me, I can't get Light set 1 to come on by itself. When I put power to 87a to test, both lights sets turn on.
What am I doing wrong?
Thanks,
Brandt
Replies:
Posted By: davep.
Date Posted: February 26, 2014 at 10:04 PM
bhamilton wrote:
For the life of me, I can't get Light set 1 to come on by itself. When I put power to 87a to test, both lights sets turn on.
What am I doing wrong?
Thanks,
Brandt
You're going to do a face-palm. The only thing you've done wrong is label your switches incorrectly. The one you're calling "switch 1" is actually #2, and the one you're calling "switch 2" is actually #1.
To turn on light set 1, in the current configuration, turn on the wrong switch 2 by itself, and Light Set 1 should come on. In your troubleshooting truth table you didn't try "Switch 1=OFF, Switch 2=ON".
That's all I see.
Posted By: bhamilton
Date Posted: February 26, 2014 at 10:09 PM
davep. wrote:
bhamilton wrote:
For the life of me, I can't get Light set 1 to come on by itself. When I put power to 87a to test, both lights sets turn on.
What am I doing wrong?
Thanks,
Brandt
You're going to do a face-palm. The only thing you've done wrong is label your switches incorrectly. The one you're calling "switch 1" is actually #2, and the one you're calling "switch 2" is actually #1.
To turn on light set 1, in the current configuration, turn on the wrong switch 2 by itself, and Light Set 1 should come on. In your troubleshooting truth table you didn't try "Switch 1=OFF, Switch 2=ON".
That's all I see.
Thanks for the reply. I'm pretty sure I tried that, but I'll look again in the morning. When I turn on switch 2, I can hear the relay flip.
Posted By: bhamilton
Date Posted: February 27, 2014 at 6:05 AM
Just checked and light set 1 does not work in any switch configuration. Lights do work when jumpered.
Posted By: bhamilton
Date Posted: February 27, 2014 at 6:56 AM
Figured it out. Had 30 and 87 swapped. 
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