71 wiring harness
Thread Starter
Pro
Joined: Nov 2008
Posts: 680
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From: Denham Springs LA
71 wiring harness
I am trying to figure out why I have low voltage at my coil.
I measured the resistance between the coil 12v wire and engine ground and read 5.4 ohms. Others on the forum have measured 2.8 ohms.
I measured the resistance between the ignition fuse and the engine ground and read 4.0 ohms. I assume these 4.0 ohms are too much. What's the most likely candidates causing the high resistance?
Don't know if it matters but one of my door ajar switches it really crushed/broken. Also my amp meter is very jittery. The rear main bearing seal leaks and keeps a film of oil on my starter and its wire connections.
Thanks
Roger
I measured the resistance between the coil 12v wire and engine ground and read 5.4 ohms. Others on the forum have measured 2.8 ohms.
I measured the resistance between the ignition fuse and the engine ground and read 4.0 ohms. I assume these 4.0 ohms are too much. What's the most likely candidates causing the high resistance?
Don't know if it matters but one of my door ajar switches it really crushed/broken. Also my amp meter is very jittery. The rear main bearing seal leaks and keeps a film of oil on my starter and its wire connections.
Thanks
Roger
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
With the harness and ignition components already wired together, you can't tell a lot with a resistance meter. Now if your engine is running and you are getting less than 7-8 volts between ground and the [+] coil terminal, the next check would be to shut the engine OFF, remove the wire from that [+] terminal (which comes from the fuse block) and measure the resistance of that wire between the connector at the end and a point near the fuse block on that same wire [note: Use a small straight pin to push through the wire insulation and into the wire; then clip one meter lead to it.] The resistance of that line should measure about 1.35 ohms. If it measures signigicantly higher (2.0 ohms or more), the manufacturer used the wrong resistance wire in the harness. That condition can be corrected, but you will need to do a simple modification to that wire.
Thread Starter
Pro
Joined: Nov 2008
Posts: 680
Likes: 5
From: Denham Springs LA
Okay i'll measure the resistance from wire end to end. I knew that, but I got conthused.
When the engine is running the voltage has been as low as 6 volts, but is usually around 8 to 9 volts. I don't understand why it vaires so much. Someone else on the forum measured the resitance through the wiring harness like I did. Where they recorded 2.8 ohms between the end of the coil resistance wire and the enginge block, and I measured 5.4 ohms. I am working out of town, bored and trying to figure it out in my mind what could be causing my additional resistance.
Thanks,
Roger.
When the engine is running the voltage has been as low as 6 volts, but is usually around 8 to 9 volts. I don't understand why it vaires so much. Someone else on the forum measured the resitance through the wiring harness like I did. Where they recorded 2.8 ohms between the end of the coil resistance wire and the enginge block, and I measured 5.4 ohms. I am working out of town, bored and trying to figure it out in my mind what could be causing my additional resistance.
Thanks,
Roger.
