Sh 775 install with SPG

[fastbysuzuki]

Hi i am about to install a SH 775 could someone please look at the sketch i have done to check i am correct with what i am about to do?
one question is about the black/white ground on the solenoid, do i remove it from the mounting and extend it to the spg?

 

[posplayr]

Hi i am about to install a SH 775 could someone please look at the sketch i have done to check i am correct with what i am about to do?
one question is about the black/white ground on the solenoid, do i remove it from the mounting and extend it to the spg?

View attachment 41539

You want to do it as shown (except the starter solenoid wire should be the harness B/W). The B/W when attached to the SPG is the ground for your entire harness. All current running through your harness end up here. If you move the B/W to somewhere else and there is a voltage drop between that B/W ring lug and the SPG then you have lowered the voltage (anything using the harness for power) across your entire harness.

The solenoid ground is secondary because as long as it sees about 7V it will trigger.

List all of the wires coming into and out of the SPG and compare to your drawing. The harness ground (B/W) is the only one discrepancy. Having done this you will probably realize why I put all except the Harness B/W into a single crimped and soldered ring lug (AWG2-4). I call this a SPG Harness. The Harness B/W just stacks on top of the single combined ring lug. You will also note that as long as the two are stacked, it doesn't matter where they are mounted as far as charging and return currents. If the solenoid is attached to the metal plate that the SPG ground screws into you don't have to worry about an additional ground for the solenoid.

 

[fastbysuzuki]

You want to do it as shown (except the starter solenoid wire should be the harness B/W).

Hi Poss thanks for the reply, the wire I called starter solenoid on my drawing is b/w and is mounted on one of the retaining bolts on the solenoid plate via a ring lug is this the harness return?? if so then I should remove it and extend it to the spg?
or is this wire not the harness return?
just trying to get it all clear in my head.

 

[posplayr]

Hi Poss thanks for the reply, the wire I called starter solenoid on my drawing is b/w and is mounted on one of the retaining bolts on the solenoid plate via a ring lug is this the harness return?? if so then I should remove it and extend it to the spg?
or is this wire not the harness return?
just trying to get it all clear in my head.

At this point I don't know where your SPG is relative to the solenoid? Regardless I'll answer as plainly as possible.
1.) You need at least one HARNESS B/W stacked on the SPG. There are normally two B/W ring lugs. On the 16V bikes they tend to be battery box and side plate where solenoid and R/R are mounted. Without looking it up I assume you have two also with the solenoid on the side plate. So where is your SPG? Battery box? Again, stack one of the B/W harness ring lugs on top of your SPG.

2.) The solenoid ground is not that important. If the Harness B/W that is not going to the SPG goes to your solenoid as a ground(??) then you are fine.

What you have not clarified is where your Solenoid is mounted in relation to the SH-775 and it's SPG. This is not super critical, but since your are going through it , it is best to just optimize the configuration.

 

[fastbysuzuki]

So where is your SPG? Battery box?

yes I am planning to mount the 775 under the battery box and use one of the mounting holes for the spg thanks

 

[posplayr]

yes I am planning to mount the 775 under the battery box and use one of the mounting holes for the spg thanks

So I assume the solenoid is not under the battery box?

So it is simple; the solenoid ground has nothing to do with the SPG. The Solenoid ground is the "other " B/W ring lug. While it would hurt nothing, there is no NEED to run the solenoid ground to the SPG. In the diagram I showed, the solenoid is not shown because it doesn't matter. The only things that matter are shown.

Make sure the battery box B/W ring lug is stacked on the SPG or at least make sure there is a good connection between the two (extend to the SPG is necessary).


For anybody else reading this and I'm sure is getting confused, this is all very easy if you simply forget everything else and just do the following.

A.) Locate the SPG no more than 1 ft from the R/R(-) . The 1 ft is the length of wire from the R/R(-) to the SPG. It does not matter what you bolt to, plastic , frame or side plate.

B.) Create a low impedance ( less than 0.05 ohms) link between all the following wires at the SPG:

1. R/R(-) 14 awg
2. Battery(-) 16 awg
3. Frame ground 16 awg
4. Harness ground B/W ring lug.

You can accomplish this with a single combined ring lug or a ring lug for each wire, but then you have to keep the ring lugs from corroding with dielectric grease of DeOxit. I recommend a single SPG ring lug for wires 1 through 3, and just stack the OEM B/W ring lug on top of it.

C.) Make sure all connections have something on them to prevent corrosion.
This includes the battery connections, the frame connections, the ring lug stack or any connectors you felt compelled to add especially if you used the SH-775 mating connector.

CONCLUSION: THAT IS ALL THERE IS TO IT for implementing a Single Point Ground. Don't over complicate it and lose sight of the 3 items mentioned.

Finally with respect to the solenoid ground, do whatever is most convenient. (use teh second B/W ring lug, add another wire, use the SPG which is already grounding the electronics plate). The solenoid ground does not need to go to the SPG and as long as it is grounded somewhere you are OK.

 

[fastbysuzuki]

So I assume the solenoid is not under the battery box?

you are correct.
i am sorry if I caused confusion but the picture I had been looking at below. number 4 caused me to think about the b/w wire mounted at the solenoid. Thanks for you patience I have got it now.

 

[posplayr]

you are correct.
i am sorry if I caused confusion but the picture I had been looking at below. number 4 caused me to think about the b/w wire mounted at the solenoid. Thanks for you patience I have got it now.
View attachment 41548

Sorry to come across frustrated, I'm really just trying to make what seems complicated easy to accomplish. I've been trying to come up with what is confusing. I guess if I had drawn many more drawings for more variations of the SPG it would be easier to understand, but even that is not clear that it would help. There is really nothing different in the picture that you attached and the description I provided nor the schematic. However, there are differences to the way you plan to wire your bike. The picture shows a solenoid and R/R on the same plate. You plan to put the solenoid on the plate and the R/R on the battery box. So there is going to be a difference in the way the solenoid is grounded. But since there are no specific directions and in fact I've said the solenoid grounding does not matter you should know that the solenoid ground does NOT necessarily have to go to the SPG.

Having said that, I can see that the picture might be somewhat confusing when you look at that black wire that is labeled HARNESS GROUND (it also says formerly solenoid ground). Normally that would be the stock OEM B/W wire ring lug coming from the harness (one of the two I have already mentioned). What is not mentioned n teh picture is that I did not really have to extend that B/W wire but I did need to replace it as on my 1981 GS750EX the two B/W ring lugs were burned. At the time I did not have a spare harness and wanting to increase the wire size (to 16 awg from 18 awg) a bit anyway, I swapped out both charred wires for the Black wire indicated.

This is not an extension of the solenoid ground (from the solenoid mounting bolt to SPG). It is a new Black ground to replaced B/W wire coming from the HARNESS as labeled. As Oldvet just mentioned again, the side plate where both the R/R and solenoid are mounted is grounded to the battery by virtue of the wire between SPG and battery(-). That is all that is needed to power the solenoid.

In your case your R/R and SPG is presumably on the battery box so how are you going to get a ground to your solenoid? Since it is non critical there is flexibility in the grounding. Grounding direct to the SPG is overkill and not necessary but it will surely work. However, more than likely there is already a B/W ring lug (the second one) already grounding the side plate and so as long as it is clean you are done.

I think the best way to avoid confusion is to visualize where the currents will flow. The SPG is primarily designed for charging currents when the alternator is producing power(these voltages are critical to proper battery charging). The solenoid really runs off battery power when the alternator is not producing much if anything during cranking(these voltages are not critical to anything).

In your case to understand the current flow through the solenoid, you just need to follow the wire going back back to return to the source. For the solenoid that is the battery.

1. Your solenoid is hard mounted and grounded to the side plate.
2. The side plate has a B/W HARNESS ground wire and current leaves the solenoid (through the mounting bolt) traveling back into the harness.
3. When the current gets to a common point inside of the harness, it flows back out the other B/W HARNESS ring lug wire towards the SPG.
4. At the SPG the current splits off and goes to Battery(-).

This might appear to be circuitous, but any time you have these dual HARNESS ground wires that is what you are going to get. Current flows into one and out the other. That is why mine burned up not damaging the rest of my harness. In a "ideal" single point ground , you would not design the harness this way, but as long as charging currents between R/R and battery are not affected there is no big downside requiring a dedicated run from the solenoid to the SPG. In fact teh SPG is for charging currents so the best ground for the solenoid is the battery (-). Since the solenoid ground is non critical just using the OEM provide B/W ring lug from teh harness is fine; it is already there. Just clean it and protect it for years of reliable service.