underdash starter relay.

[IRWFO]

Here's an idea, do away with the relay altogether and replace it with a push button switch on the 24v wire. You push the button and the starter will engage, release and starter disengages. The 12v wire would be disconnected.

Well it is nice to use the key switch like intended.

 

[GreenBull]

I still believe the OP describes an abnormal condition. The modification suggested will likely solve the problem but only a qualified diagnoses can determine that.

Myself I'm going to use the same relay that I retrofit in for the glow plugs on my M1028. I still haven't decided what part # I'll be using but I'm thinking it's better to use a common part for both these applications as they are very similar.

There are pictures posted on this site or the SS CUCV archive of a Ford starter or glowplug type relay installed in this application.

This 12v relay control of a 24v solenoid type starter circuit and a 12v blower motor relay circuit are very different. There is a big difference in the contact arcing characteristics of relay in a motor vs a solenoid coil circuit . I kind of question the recommendation in the FAQ to use the Ford blower relay.

The 'heavier' relay is a good modification. You might be able to solve the relay failure issue by installing a point ignition type condenser but I'm not going to try because I don't have any left (charged them and threw them at people I didn't like) and it's not like there is a weight/space issue on the CUCV.

I assume the circuit is protected with a fuse link at the 24v bus (haven't looked at the schematic in 20+ yrs) but would also like to caution that installing a relay with open stud type connections in a metal dash without securing it properly is bad juju...

Sarge,

I'm an ASE master car and truck (I need to take the new car diesel test this spring though).

I got my SF97, bill of sale, and Florida title reassignment yesterday and got a plate today. I'll start working on my truck when it gets warmer.

THE FOLLOWING STATEMENTS HAVE NOTHING TO DO WITH ANY THREAD ON SS OR ANY SS MEMBER.

No worries about hurt feelings. I've gotten good info from SS and I'll give some back. I've been at this long enough to know that you can lead a horse to water, shove his nose down in to give him a taste (as appropriate), and that there isn't one more @&#$ thing to do about him wading in and drowning himself or dying of thirst after...

 

[GreenBull]

I looked at the schematic and it shows a radio suppressor between the 24v and ground busses in the starter schematic. A failed suppressor may contribute to relay contact arcing.

 

[realm]

Is the AC40 or whatever better than stock or do they blow too?

 

[underdog]

Well this is the Solenoid i will install one day.
SPST 24V 85A Insulated Continuous Solenoid
I to, have had alot of failures, and keep a spare in the glove box.

And i hope i am an asset not a liabilty to the workings of this forum.
I try to stay in the back row

 

[doghead]

Yesterday, I did change mine out for a higher capacity relay. I will post a thread soon, with all the details. I do want to add, two protective covers to the top two studs(like the rubber boots used on the alternator positive battery terminals). But for now, it is done and I won't worry about failures of this component. I choose this relay(instead of the style shown above"the Ford style"), because it fit nicely in the original location. It is rated at 200 amps, intermittent. Here's 2 pics of it, for now.

 

[underdog]

doghead
That is good work and nice camera skills.

 

[davo727]

I thought I saw that the triggering voltage for our relays is 12 volts ? If so the relay you posted will not work if it has a 24 volt pull down coil in it.

Well this is the Solenoid i will install one day.
SPST 24V 85A Insulated Continuous Solenoid
I to, have had alot of failures, and keep a spare in the glove box.

And i hope i am an asset not a liabilty to the workings of this forum.
I try to stay in the back row

 

[realm]

Is the starter relay primarily used to convert the 24volts to 12volts or what?
If you do a 12volt conversion do you bypass the relay?

 

[doghead]

Is the starter relay primarily used to convert the 24volts to 12volts or what?
If you do a 12volt conversion do you bypass the relay?

It does not convert, it is a relay.(an electronically activated switch)

The starter relay is triggered by 12v, and it switches 24v(the key switch applies 12V to the relay coil, closing the contacts and the contacts are supplied with 24v and that in-turn goes to the starter solenoid).

If you convert your truck to 12V(all of it), you could leave the relay in ,or you could remove the relay completely and jumper the purple w/white stripe wire to the purple wire. It depends on how you want to(or are told to) do it.

 

[realm]

Got it... thanks, and is the starter solenoid the thing mounted on top of the starter itself? Usually when I've seen them they're on a firewall.

 

[doghead]

Got it... thanks, and is the starter solenoid the thing mounted on top of the starter itself? Usually when I've seen them they're on a firewall.

Yes, the starter solenoid is mounted on top of the starter. It does a couple of things. It moves the bendix drive to engage the starter pinion gear with the flywheel/flex-plate ring gear. It also makes and electrical connection, to power the starter motor.



The ones you have seen on the fender or firewall("ford style relays") are technically called a "relay". They simply switch power.

The solenoid is called a solenoid, because it moves something, mechanically(the bendix).

 

[realm]

Awesome, thanks for educating me.

 

[realm]

doghead,

Does your new relay have the purple wires going to the same terminal, or separate?
Looks like...
Red to right bottom
2 purples to left bottom
black to left top
and nothing on the right top

Or does one of the purple go to right top?
How do you know which one?

Thank you!

 

[Crash_AF]

The relay doesn't care which terminal the wires go on, as long as both 12V are on the small ones and both 24V are on the big ones.

Black and purple/white on the small terminals
Red and purple on the large terminals

Later,
Joe

 

[doghead]

I changed the picture above, to one that is less confusing(sorry). In the new picture, it is now obvious where each wire goes. The "lower" purple wire has a white stripe.

Here is a description of each wire.

Top post ,red, 24v+ supply
Top post, purple, to starter solenoid
Bottom post, purple with white stripe, 12V + from key in start position
Bottom post, black, chassis ground (12v negative)

Be sure to remove BOTH, your front battery negative battery cable and your rear battery positive cable, while doing this modification.

Same picture as above, to make it easier to read this and see the picture.

 

[doghead]

Here's an enhanced pic!

Be sure to right click on it and "open in new window" for better resolution.

3 wires are Positive, and one negative(not clear when you expand the pic on the SS site)

 

[realm]

doghead's my hero. That writeup is so good you should probably put it in its own thread.

How is the relay working so far by the way?
This is on my to-do list for this weekend.

 

[doghead]

Thanks, I do plan to write a thread on it eventually. It is working well, I have about 100 starts on it so far, and I like it a lot! It sounds off a reassuring snap every time I turn the key. I have 100% confidence in it.

btw, the enhanced picture was sent to me by mistaken1, Thank you

 

[underdog]

Yesterday, I did change mine out for a higher capacity relay. I will post a thread soon, with all the details. I do want to add, two protective covers to the top two studs(like the rubber boots used on the alternator positive battery terminals). But for now, it is done and I won't worry about failures of this component. I choose this relay(instead of the style shown above"the Ford style"), because it fit nicely in the original location. It is rated at 200 amps, intermittent. Here's 2 pics of it, for now.

Well my luck is holding.
After yet another burned up.
I stopped by the parts store and picked up a ford type solenoid.
Went out today and wired it up (same as above) and ...................... nothing
Tested everything:
24 volt power - check
12 volt signal from ignition switch - check
Ground - check
Power wire out to starter still intact - Check
Try another solenoid - still nothing
Swap wires to every possible combination - still nothing
Dig in box for directions. looks as it should - still nothing
So i ran two extra wires up thru the radio hole (power in and power out) tied them off. Marked the hot and put a wire nut on it.
put it back together.
Pull the cap; spark the wires and .............. Varoom, clatter clatter, belching smoke; ready to go.
I got it working.............................................
Just not the finished product i had invisioned.