-
Welcome back Guest! Did you know you can mentor other members here at H-M? If not, please check out our Relaunch of Hobby Machinist Mentoring Program!
Had an odd problem today with some wiring
- Thread starter alloy
- Start date
- Joined
- Jul 5, 2014
- Messages
- 2,776
The ground wire for the fan and horns was a 10awg wire. I guess there could have been resistance in the crimped connection. This wire didn't go through a ground block, but directly from the fan and horns to the engine block. The ground block is used for other things and it was a shorter run of wire to get the the engine block instead of the ground block. And I'm doing my best to hide as many wires as I can. I totally hate wires hanging out everywhere. Looks too backyard to me like that.
I'm a big fan of using my DWM to check connections. That's how I traced the problem to the ground wire and not the steering column where I originally thought the problem was. I probably don't use but 1% of the capabilities of the DVM, but I can use it to check voltages, check resistance, and continuity. I know it's capable of much more, but I've only needed it for this up to now.
I'm glad my guess about the least path of resistance was correct. I'm learning more as I go. This is the second car I've done a full wiring harness on.
Funny, I remember just a short time ago I was trying to figure out how to wire up a relay and use a temp switch ground to turn the relay of instead of power to energize it. I just talked a guy through a double relay install to control his cooling fan where one relay was turned on by the AC coming on, and the second relay was turned on by a normally open temp switch that closes and provides a ground to tun the second relay on. Both relays are going to be us to turn on the same fan.
The diagram that American autowire gave him sucked. Now it's obvious what they were trying to explain to me, but a short time ago it wasn't.
I think the old saying is wrong, You can teach an old dog (me) to do new tricks
I'm a big fan of using my DWM to check connections. That's how I traced the problem to the ground wire and not the steering column where I originally thought the problem was. I probably don't use but 1% of the capabilities of the DVM, but I can use it to check voltages, check resistance, and continuity. I know it's capable of much more, but I've only needed it for this up to now.
I'm glad my guess about the least path of resistance was correct. I'm learning more as I go. This is the second car I've done a full wiring harness on.
Funny, I remember just a short time ago I was trying to figure out how to wire up a relay and use a temp switch ground to turn the relay of instead of power to energize it. I just talked a guy through a double relay install to control his cooling fan where one relay was turned on by the AC coming on, and the second relay was turned on by a normally open temp switch that closes and provides a ground to tun the second relay on. Both relays are going to be us to turn on the same fan.
The diagram that American autowire gave him sucked. Now it's obvious what they were trying to explain to me, but a short time ago it wasn't.
I think the old saying is wrong, You can teach an old dog (me) to do new tricks
- Joined
- Jul 5, 2014
- Messages
- 2,776
After helping the guy with his 2 relay setup I realized that I didn't have my fans set up to come on when the AC is on.
I have the 75 amp breaker that controls both fans setup with a ground trigger. The adjustable temp switch has one wire to ground, and the other one to the ground post of the relay.
So I had to figure out how to use 12V power from the AC compressor to supply a ground to turn the main relay on. So I added a 30 amp relay and ran the 12V from the AC compressor to pin#86, and a ground to pin#85. This allowed the relay to be turned on when the AC is on. Then pin#87 to ground, then pin#30 to the main relay ground. Apparently pins #87 and pin#30 are isolated from the rest of the relay so you can run power through it, or use it to supply a ground like I did. Amazingly enough it actually works and I didn't burn anything up this time.
Learn something new everyday.
I have the 75 amp breaker that controls both fans setup with a ground trigger. The adjustable temp switch has one wire to ground, and the other one to the ground post of the relay.
So I had to figure out how to use 12V power from the AC compressor to supply a ground to turn the main relay on. So I added a 30 amp relay and ran the 12V from the AC compressor to pin#86, and a ground to pin#85. This allowed the relay to be turned on when the AC is on. Then pin#87 to ground, then pin#30 to the main relay ground. Apparently pins #87 and pin#30 are isolated from the rest of the relay so you can run power through it, or use it to supply a ground like I did. Amazingly enough it actually works and I didn't burn anything up this time.
Learn something new everyday.
Last edited: