Volt meter drops 90 flhtcu
Road Master
Joined: Aug 2007
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Yeah, Paco, like the phone company, I'm here to help. Actually, teh intraw3bz, y0, have increased the efficiency of our society tremendously. For good and bad, it seems, as the bankers are now more efficiently screwing us to the wall. Anyway, at least we can share how-to's for things that we've been there on. It's the same with my cars on their specific forums. I've been riding Harley's since 1979. Way before I became a doctor. I guess I did it backwards there.
Anyway, JG, I wrote a rough tutorial/guide and posted it here somewhere on how to add an extra relay. Here it is again:
How I Added The Extra Relay.
First off, buy a relay at the auto parts store. I used one that is the same as the regular start relay, located under my right side cover, bolted to the oil tank. You can get the part number off the old relay and have them cross it. It's a common relay and not expensive. Two types are available, one that has a screw mount like the original and one without. Get the screw mount one. Relay sockets are available as well, or you can use wire flag type connectors and push them on the relay terminals directly. Pull the seat off. Mount the relay to the inside of the left panel using a screw that holds the rear brake MC reservoir on. Run a heavy gauge wire from the starter solenoid post that goes to the battery, like 12ga. Put a fuse in the line, like 20 amp or so. You can get a inline fuse holder for the newer automotive flag fuses at radio shack. Connect the other end from the fuse to a normally open post of the relay. Connect the opposite post (the one that connects to the normally open one when the relay is energized) to a heavy wire running down to the small wire post on the starter solenoid. Leave the original small wire there too. Now you only have to energize the new relay. Run a wire (can be smaller, like 16 ga smaller if you wanted) from the starter relay coil to the coil of the new relay. You can run both sides, or one side and ground the other, whatever you want. This way, when the starter relay is energized by the rest of the bike (push button, etc.), both relays engage in parallel and both relays put +12V on the solenoid coil. The new relay puts a full +12V without any of the dozen electrical connections and little bits of wire in the way. It is fused so that if something bad happens, the fuse blows and not the battery (or wire, more likely). When you're testing it, have the battery cables somewhat loose on the battery so you can pull them and stop the whole system should you have screwed up the wiring somewhere.
Anyway, JG, I wrote a rough tutorial/guide and posted it here somewhere on how to add an extra relay. Here it is again:
How I Added The Extra Relay.
First off, buy a relay at the auto parts store. I used one that is the same as the regular start relay, located under my right side cover, bolted to the oil tank. You can get the part number off the old relay and have them cross it. It's a common relay and not expensive. Two types are available, one that has a screw mount like the original and one without. Get the screw mount one. Relay sockets are available as well, or you can use wire flag type connectors and push them on the relay terminals directly. Pull the seat off. Mount the relay to the inside of the left panel using a screw that holds the rear brake MC reservoir on. Run a heavy gauge wire from the starter solenoid post that goes to the battery, like 12ga. Put a fuse in the line, like 20 amp or so. You can get a inline fuse holder for the newer automotive flag fuses at radio shack. Connect the other end from the fuse to a normally open post of the relay. Connect the opposite post (the one that connects to the normally open one when the relay is energized) to a heavy wire running down to the small wire post on the starter solenoid. Leave the original small wire there too. Now you only have to energize the new relay. Run a wire (can be smaller, like 16 ga smaller if you wanted) from the starter relay coil to the coil of the new relay. You can run both sides, or one side and ground the other, whatever you want. This way, when the starter relay is energized by the rest of the bike (push button, etc.), both relays engage in parallel and both relays put +12V on the solenoid coil. The new relay puts a full +12V without any of the dozen electrical connections and little bits of wire in the way. It is fused so that if something bad happens, the fuse blows and not the battery (or wire, more likely). When you're testing it, have the battery cables somewhat loose on the battery so you can pull them and stop the whole system should you have screwed up the wiring somewhere.
Thanks for the tutorial. What exactly does this relay do? Sounds like it provides more power to the starter solenoid. I don't have any problems with starting. I have problems with my voltmeter jumping all over the place. Thanks!
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,200
Likes: 3,089
From: NW AR
JG, that's the relay under the seat that I and some others have done, and that's exactly what it does, that is, provide full battery power to the starter solenoid, ending The Dreaded Click.
The volt meter jumping can be a lot of things, as mentioned in this thread, from "they all do that" to a short somewhere. The important thing about the volt meter is to just monitor it for changes, not absolute values. If it didn't used to jump around and now does, that's a change. I strongly suspect the original poster of this thread ("George Williams") was a troll.
The volt meter jumping can be a lot of things, as mentioned in this thread, from "they all do that" to a short somewhere. The important thing about the volt meter is to just monitor it for changes, not absolute values. If it didn't used to jump around and now does, that's a change. I strongly suspect the original poster of this thread ("George Williams") was a troll.
HDF Community Team
Joined: Dec 2005
Posts: 5,421
Likes: 2,621
From: NC USA
Here is a (primative) drawing of how the accessory / start circuit is wired on Late Shovels and Evo Touring models. This does not apply to Softtails or any others with a tank mounted or under seat ignition switch which use a 4 pole starter relay. You can see there are no less than 10 connection points before voltage ever gets to the load side of the accessory breaker and at least 9 before it reaches the starter solenoid. You will also see that the starter relay disconnects power to the entire accessory circuit when the starter button is pushed, engaging the starter relay/solenoid. Also, the voltmeter is on the very end of the wiring that feeds the accessory items.
One solution is to add a relay under the seat, use the wire that attaches to the "bat" side of the relay as the trigger wire for the added relay and route power from that relay directly from the main breaker back to the acc breaker. And/or, you could route the power directly to the "feed" wire of the starter relay. Alternatively, you could use the trigger wire of the starter relay, to energize the added relay and send power directly to the starter solenoid, bypassing the acc circuit alltogether or in conjunction with the original wiring. (I think that's what DrHess did)
One solution is to add a relay under the seat, use the wire that attaches to the "bat" side of the relay as the trigger wire for the added relay and route power from that relay directly from the main breaker back to the acc breaker. And/or, you could route the power directly to the "feed" wire of the starter relay. Alternatively, you could use the trigger wire of the starter relay, to energize the added relay and send power directly to the starter solenoid, bypassing the acc circuit alltogether or in conjunction with the original wiring. (I think that's what DrHess did)
Last edited by t150vej; May 6, 2010 at 08:50 AM.
Road Master
Joined: Aug 2007
Posts: 848
Likes: 8
From:
Here is a (primative) drawing of how the accessory / start circuit is wired on Late Shovels and Evo Touring models. This does not apply to Softtails or any others with a tank mounted or under seat ignition switch which use a 4 pole starter relay. You can see there are no less than 10 connection points before voltage ever gets to the load side of the accessory breaker and at least 9 before it reaches the starter solenoid. You will also see that the starter relay disconnects power to the entire accessory circuit when the starter button is pushed, engaging the starter relay/solenoid. Also, the voltmeter is on the very end of the wiring that feeds the accessory items.
One solution is to add a relay under the seat, use the wire that attaches to the "bat" side of the relay as the trigger wire for the added relay and route power from that relay directly from the main breaker back to the acc breaker. And/or, you could route the power directly to the "feed" wire of the starter relay. Alternatively, you could use the trigger wire of the starter relay, to energize the added relay and send power directly to the starter solenoid, bypassing the acc circuit alltogether or in conjunction with the original wiring. (I think that's what DrHess did)
One solution is to add a relay under the seat, use the wire that attaches to the "bat" side of the relay as the trigger wire for the added relay and route power from that relay directly from the main breaker back to the acc breaker. And/or, you could route the power directly to the "feed" wire of the starter relay. Alternatively, you could use the trigger wire of the starter relay, to energize the added relay and send power directly to the starter solenoid, bypassing the acc circuit alltogether or in conjunction with the original wiring. (I think that's what DrHess did)
Where exactly is the main breaker coming from the starter solenoid located? Is it one of the 4 breakers that are located under the fairing? The first one on the left when looking straight at the front of my bike has 3 red wires on it. 2 on one pole and 1 on the other. This is the wire that was pretty darn warm when the bike was running for only about 10 minutes tops. If it is.. my guess is the reason it was warm is because my bike still has the original 20 year old battery cables on it and when I peeled back the insulation they were in fairly rough shape at the ends. Also.. although my bike starts everytime, sometimes it just clicks/compression pops/very breifly hesitates and starst and other times it just starts instantly with no hesitation. If I have capacitance (or resistance) because of battery cables that are starting to fail wouldn't that cause the problems I am experiencing?
Thanks for the great diagram!!!
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,200
Likes: 3,089
From: NW AR
The main breaker on my bike is under the seat. I dunno about yours, but I'd look in that area, and if you see a single breaker near the battery, that's probably it. Be careful of your terminology. Battery cable capacitance is a totally different thing and unrelated to any issue we would experience with our bikes.
Corroded cables should be replaced or repaired. A wire, breaker, connection, etc. that is warm is a sign that there is resistance at that point. If it is not supposed to have resistance, like being a wire, breaker, connection, etc., then there is a problem there and it should be replaced. Some things have resistance for whatever it is they do (everything has some resistance except superconductors, but that's another topic again), so some heat is expected, it's just that a battery cable, for example, should have low heat on it versus, say, a solenoid coil that's on.
Corroded cables should be replaced or repaired. A wire, breaker, connection, etc. that is warm is a sign that there is resistance at that point. If it is not supposed to have resistance, like being a wire, breaker, connection, etc., then there is a problem there and it should be replaced. Some things have resistance for whatever it is they do (everything has some resistance except superconductors, but that's another topic again), so some heat is expected, it's just that a battery cable, for example, should have low heat on it versus, say, a solenoid coil that's on.
HDF Community Team
Joined: Dec 2005
Posts: 5,421
Likes: 2,621
From: NC USA
JG, I either don't know or can't remember which bike you have, but they are generally under the seat all by themself. There's one wire coming from the starter/battery connection and one going to the main switch and a 3rd that comes from the regulator, on the "load" side but sometimes they get connected to the wrong side of the beaker (doesn't hurt anything unless the reg/wire shorts out). In the dash or fairing, there is one for constant power (radio memory), acc, ign and lights and unless it's been removed, there is a jumper between the light and ign breakers. There are a few exceptions but that covers 99% of the Evo and late Shovel FL Touring models (not FLSTs)
Also, a weak or corroded breaker or terminal connections there will generate heat in the wires on that circuit near to the breaker.
Also, a weak or corroded breaker or terminal connections there will generate heat in the wires on that circuit near to the breaker.
Last edited by t150vej; May 9, 2010 at 08:45 AM.
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Road Master
Joined: Aug 2007
Posts: 848
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From:
The main breaker on my bike is under the seat. I dunno about yours, but I'd look in that area, and if you see a single breaker near the battery, that's probably it. Be careful of your terminology. Battery cable capacitance is a totally different thing and unrelated to any issue we would experience with our bikes.
Corroded cables should be replaced or repaired. A wire, breaker, connection, etc. that is warm is a sign that there is resistance at that point. If it is not supposed to have resistance, like being a wire, breaker, connection, etc., then there is a problem there and it should be replaced. Some things have resistance for whatever it is they do (everything has some resistance except superconductors, but that's another topic again), so some heat is expected, it's just that a battery cable, for example, should have low heat on it versus, say, a solenoid coil that's on.
Corroded cables should be replaced or repaired. A wire, breaker, connection, etc. that is warm is a sign that there is resistance at that point. If it is not supposed to have resistance, like being a wire, breaker, connection, etc., then there is a problem there and it should be replaced. Some things have resistance for whatever it is they do (everything has some resistance except superconductors, but that's another topic again), so some heat is expected, it's just that a battery cable, for example, should have low heat on it versus, say, a solenoid coil that's on.
Seasoned HDF Member
Joined: Aug 2007
Posts: 8,200
Likes: 3,089
From: NW AR
If the entire wire is hot, and not just hot at the end, then that indicates either a wire improperly sized (too small) for the circuit load, or a circuit load over the design spec. As others have not noticed a problem there, I'm going with too much juice in that circuit. Now, why? Is something shorting in that circuit? Is there a huge radio or amp on there, or extra lights? One or the other.