Where does the purple wire go exactly?

[mistaken1]

It looks to me like you are putting two coils in series. The coil (solenoid) on the starter (24V) and the ford coil (12V or 24V ????). When you put two coils in series they share the available voltage, which means neither one gets the proper voltage to operate.

The starter solenoid is designed to work at 24V. If you have 24V on the purple wire at the starter solenoid that solenoids path to ground passes through the ford relay where it is designed to work at ?? volts.

Assuming your ford relay is 24V your coils need to be in parallel.

According to the attached diagram when you send voltage to “S” on the starter solenoid the path goes through a solenoid coil to “M” on the attached diagram and then through the contacts back to “B” on the solenoid and to “S” on the relay through that relay coil and then from “I” on the relay to ground (negative).


I still do not understand how this is supposed to solve any heat issues as the starter and its solenoid are still together and still subject to heat.

As doghead pointed out the stock CUCV system already implements this relay control of the power going to the starters as part of the 24V starting system. If you are concerned about heat in the wires that feed the starter and its solenoid then just replace them with larger wires in the stock control configuration. The whole point to the doghead modification is to replace the stock starter relay with a heavy duty unit which is what you are trying to do with the ford relay. Why try to reinvent the wheel?

As far as heat goes unless you are running headers that sit close to the starter generating more heat in a closer proximity to the starter than the original design why waste time and money changing something when these trucks have been starting in their stock form for 25+ years?

Not picking on you, I just don't understand why you want to do what you want to do, none the less I will do what I can to help you accomplish your goals.

 

[edpdx]

Mistaken1, thanks for the help. I am not trying to beat the heat issue with a remote. Here is a link to a thread about this remote diagram I propose. I hope it will make things clear about why I wanted to go this route.

The info you provided is interesting. If you think my idea has merit, I'd like to give it a try. Maybe you can suggest a parallel schematic that will work.

LINK to original thread

 

[mistaken1]

If you are burning up starter solenoids there is something wrong.

Have you done the doghead modification? If not start there.

The voltage you read from the front battery negative to the back battery positive is the voltage you should see on the large red wire to the starter. You should see that same voltage on either side of the doghead relay (when cranking the engine). You should see that same voltage on the "S" terminal of the solenoid (when cranking the engine). (you can disconnect the large red wire from the starter when testing so the starter motor will not turn when testing)

If you do not have battery voltage or something very close to that you have too much voltage drop in the wires and relay contacts and need to correct that issue. If your voltages are good then you need to check the starter to flexplate clearance as per the TM.

Any number of people on this forum have CUCVs that are not burning up starter solenoids. It is not a design issue other than the 24V relay that the doghead modification addresses. It is something unique to your truck, we just need to find it.

Again my advice is check voltages (low voltage can destroy solenoids as the current needed to make the contacts pull in and hold tight is not there) and check the flexplate clearances as mechanical binding can keep the solenoid from disengaging properly.

Contacts need to snap in and snap out quickly to keep arcing to a minimum. Arcing destroys the contacts, it creates more arcing leading to more damage leading to more arcing leading to more damage until they unit fails completely.

Batteries can show good voltage but if bad that voltage drops quickly when placed under a load (like glow plugs and starters at the same time).

Starter motors can spin just fine when on a bench but draw excessive current when placed under load (like turning the engine over). Excessive draw from a starter motor can lower the voltage to the solenoid (along with everything else) plus pull more current through the solenoid contacts than they were designed to handle leading to early failures.


Doghead's link in post 38 shows the wiring diagram to allow a third relay. I will make a better drawing when time allows.