I have a question that I think was brought up before.

I understand the relay and I believe it was necessary to incorporate into the remote start but for those without a remote start is the relay necessary?

Why not just use a DPST switch between the pot and the APPS wiring. You would lose the remote turn on/off feature, but this should work fine for those that only want an on off switch correct?

This would simplify things for most people correct. Am I trying to make this too simple.

 

I'm not sure I'd try it. My concern would be running wires into the cab for the DPST switch may add too much resistance and bleed off power from your APPS and cause a "low" or erratic idle. Know what I mean... For the sake of "argument", lets say that the two wires in the relay circuit both carry a signal voltage of .43 volts which tells the ECM to idle the truck at 900RPM. If you add 4 feet of wire, then lets say that drops the voltage to .37 volts. The ECM is gonna either freak out and throw a code, or the truck will idle funny, or the truck won't start, or it COULD remain normal. From what they found on the TDR, if the ECM doesn't see .43volts, it freaks out.

My .02 says thanks for trying to K.I.S.S the project, but relays are cheap and easy to wire.

Also, for a little clarification, My remote start has it's own relay for engaging the high idle. Essentially, where you have an on/off switch (see diagram), I'll have an ADDITIONAL relay.

Hope that sheds a little light... also hope my post isn't inflamatory. Just trying to 'splain it the best I can.

Andy

 

BTW, here's a FANTASTIC guide to the wonderful world of BOSCH relays:

http://dlcparts.com/images/BoschGuide.pdf

It's 44 pages of nothing but how the SPDT BOSCH relay works and different things you can do with it. REALLY COOL Stuff.

Another good site for interesting automotive electronics is www.the12volt.com

 

Ok. For those like me that can't read a wiring diagram to save their lives let me see if I've got this figured out. Pin 3 goes to the Signal prong on the relay, pin 4 goes to the ground on the relay, pin 5 goes to the supply, and then we run a 12v battery to the 12v prong on the relay. Or am I completely backwards here?

 

Ok having problems getting power to run 'through' the LED and click the relay... Seems I am doing something wrong... Tried it in both directions...

 

Just refer to post 54. You basically connect it to the power and ground sources for the relay and take it out of being inline. Works flawlessly.

 

Makes sense thanks!!

What is the purpose of the resistor between ground switch and the relay?

 

Yeah.....i dont know why i never noticed that....but i dont get it either? The ground is strictly for the relay....not anything else.

 

Thank you for your comments and that is a valid concern. I will figure out the resistance over 6-8 feet for a couple different gauges of wire. I think I can minimize the voltage loss over this short distance

The one member here has his bo in the cab and no ill effects. I don't see how this would be any different except for the lack of a relay.

I think I am going to have to try this as well

This is almost too easy for those who do not need the ability of a remote turn on/off.

 

agreed. I also don't THINK you're going to hurt anything by trying it out.... so go for it!

 

Alright I have a couple of these built now... Finally!! It's dang cold outside and I was wondering if there is any way I can test this in the house?? Some kind of test using the meter?? I can test the relay and the LED fine just using an old 9V and it's working fine (the most simple part of this project!) How do I go about testing the POT and inline resistors to make sure I have things wired up correctly??

Also what gauge wire is needed for running this in-cab?? I plan on using this as an adjustable high idle only, no cruise function so RPM over 1500 is not necessary. Soooo extra loss in voltage from extra length or smaller gauge wire could be made up by simply turning the POT up a little higher correct??

Need direction!!

 

Another question. What wire from the relay/pot goes to what wire on the APPS?

 

This is correct but the POT will not be activatied at all times and this could pose a potential problem. When the POT is off the extra length of wire will still be on the APPS wiring creating some type of resistance. This is the concern Andy was pointing out.

If one is going to run this setup in the cab, I see absolutely no reason to use a relay, unless you still want the remote turn on/off feature. Other than that the relay just help you keep the wiring to the APPS as short as possible.

I am going to try just a DPST switch and POT today with a minimum of 14AWG wire running from the APPS to the switch in the cab.

 

See if this helps...

Someone else MAKE sure I've got the right pin assignments! LOL.

 

THERE IS THE MONEY SHOT RIGHT THERE! haha.....I havent check for pin placement yet.......

I might try it without the relay as well.......and just use a swith to brake power to the POT.......i will get my meter out and see what i get for resistance with my set up.....guess i will use a heaver gauge wire so loss is not as much of a concern......