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Winch relay and Ext Idle

Corprin

NAXJA Forum User
Location
MLPS
I have a multi-mount winch for my '99 XJ. I currently have the winch wired through an Andersen plug on the front bumper for quick disconnects. The Andersen plug also mates to a set of 20' jumper cables. I don't like having a large gauge wire set directly hooked to the battery at all times. I picked up a 500amp (constant) 12v isolation relay for the project.

I came up with this diagram, and wanted to shoot it across you folks.

Wiring-1.png


The idea is to trigger the isolation relay, and energize the winch (+) line only when the Ext Idle switch is engaged. I will never be jumping or winching without the idle switch on anyway, so it seems to be a logical idea. I will be wiring the hot lead of the trigger through a 10amp feed out of the PDC. The relay instructions say it will draw as little as 1amp when engaged, so I am not too afraid of popping fuses when I flip it on.

My fear is the 12v from the trigger circuit back flowing up into the ECU for some reason or another. Is this something I should fear, and soldier in a diode to prevent this from happening? What voltage flows up/down the Ext Idle circuit? Or am I just over thinking this and should just follow the pictured diagram (with the added fuze on the trigger line)?
 
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I don't like having a large gauge wire set directly hooked to the battery at all times. I picked up a 500amp (constant) 12v isolation relay for the project.
My fear is the 12v from the trigger circuit back flowing up into the ECU for some reason or another.

I agree on not wanting the Anderson plug to remain hot and accessable, there are some real jerks out there. I have seen a winch control plug hot wired, with a piece of wire, so the winch runs,and then the perpetrator walked off while the winch burned.

A 5-amp diode cost about $3, cheap insurance that nothing bad happens. The ECM is too expensive to take chances with.
You could use a single-throw, double-pole switch (STDP), wired so the ECM and battery relay are not connected when the switch is off, eliminating feedback problems.
 
With that wiring there is a good chance that you will throw a CEL shortly after you energize the circuit.
Agree with others that a separate ground switch should be wired in and consider fusing the 12V +/- to safe off the charging system if that relay overheats.
We had a local Jeep owner who had an electrical fire in the engine compartment while the Jeep was parked in the garage. If he had fused off the relay; the fire wouldn't have occurred.
 
A 5-amp diode cost about $3, cheap insurance that nothing bad happens. The ECM is too expensive to take chances with.
You could use a single-throw, double-pole switch (STDP), wired so the ECM and battery relay are not connected when the switch is off, eliminating feedback problems.

How about using a SPST relay inline with the splice on the ground switch to the ECU? The extended idle switch would still function as normal, but close the relay keeping the winch trigger line isolated from the ECU line all together. Something more like this...

Wiringa.png


Ext. idle only functions when in Park.

My 2001 also does it in neutral.

The extended idle in my 99 works in park and neutral, but that doesn't really matter. The ext idle switch is a SPST, on or off, letting the ECU "see" ground when the switch is closed. The high idle is only engaged and IF the ECU also "sees" that the trans is in Park or Neutral. IF the trans is in gear it will prevent the idle bump in the ECU, but the switch will still show ground to the ECU. The logic is in the ECU, not the switch.

The only difference between park and neutral is the position of the parking pawl.

Self recovery with a winch is not always possible when in neutral.

Unless the OP plans on installing a very large relay to handle the amp load across the contacts, I'd say don't bother.

With that wiring there is a good chance that you will throw a CEL shortly after you energize the circuit.
Agree with others that a separate ground switch should be wired in and consider fusing the 12V +/- to safe off the charging system if that relay overheats.
We had a local Jeep owner who had an electrical fire in the engine compartment while the Jeep was parked in the garage. If he had fused off the relay; the fire wouldn't have occurred.

What would cause the CEL?

Isolation relay is rated at 500amp constant, with my winch drawing 370amp at full pull (10k) I am not too worried about it overheating. Also, the relay is only there to energize the hot lead to the bumper mounted Andersen plug when the extended idle switch is closed. IF the winch is mounted and plugged in, there is circuit isolation in both the relay and the relays in the winch's box.

The switch and isolation relay is only there so I don't have to pop the hood and fiddle with wiring in order to use the winch or jump somebody. Just flip the switch on the dash, and the line is hot for what ever I need it.
 
Your first diagram looks sound, I'd just put a diode inline between the switch and the relay to prevent the fly-back voltage from spiking the ecu.

http://en.wikipedia.org/wiki/Flyback_diode

With some sleep I noticed the second diagram will not work unless the ignition is on, and the ECU is working properly... something I don't want to chance.

Came up with this one, and will be wiring that up, thank you for all the help!

Wiring-3.png
 
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