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Wiring a high idle switch?

Spanky414

NAXJA Forum User
I've read that the cop XJs had a switch that would set the idle a bit higher for running the lights and radios and such and that you could wire one in yourself.

Does anyone have the info of what I would be wiring the switch up too?

Thanks.
 
Spanky414 said:
I've read that the cop XJs had a switch that would set the idle a bit higher for running the lights and radios and such and that you could wire one in yourself.

Does anyone have the info of what I would be wiring the switch up too?

Thanks.


It must some how control the idle motor in the throttle body. It would be cool to get the kit from the dealer, I think I looked into this a long time ago and came up with nothing.

good luck and let us know what you find

james
www.geocities.com/jammerjamesharmon
 
Only person I know that has a police model, has a 93, not much help for the Renix. Have seen a schematic (for the 88) that shows the D2 pin at the ECU, retracts the IAC when the A/C is turned on.
Would probably have to install a diode, to keep the power from flowing back into the A/C wiring, if you installed a switch, suppling power to the D2 pin.
I finally got my 88 to idle at about 750-800, don´t really need the high idle anymore.
 
It is real easy. Find the pressure switch on the power steering pump. All you have to do is short across the switch. The function of the switch is to bump the idle if you turn the wheel all the way to one side and stall the power steering pump. If the idle wasn't bumped, the engine would die. It is also connected to the AC compressor switch so if the compressor kicks in at an idle, it wouldn't die.

It's a nice mod especially if you have a manual tranny. No big help if you have an auto.
 
old_man said:
It is real easy. Find the pressure switch on the power steering pump. All you have to do is short across the switch. The function of the switch is to bump the idle if you turn the wheel all the way to one side and stall the power steering pump. If the idle wasn't bumped, the engine would die. It is also connected to the AC compressor switch so if the compressor kicks in at an idle, it wouldn't die.

It's a nice mod especially if you have a manual tranny. No big help if you have an auto.

Thanks for the info, why do you say its no big help if you have an auto though?
 
All '91 and newer have a pin in the ECU that needs to be grounded for extended idle. That's what the police switch hooks up to. I don't remember which wire it is, do a search, it's out there somewhere.
 
ZmOz said:
All '91 and newer have a pin in the ECU that needs to be grounded for extended idle. That's what the police switch hooks up to. I don't remember which wire it is, do a search, it's out there somewhere.

Ah crappy, I have an 88, it could be handy for my friend with a 92 though. As for doing a search, I've done tons, I must not be putting in the right keywords.
Thats why I asked.
 
Well, i'm not sure for all years, but on 99-01 atleast it's a gray wire in pin 12 of the black connector on the PCM...I'll try and find out if it's the same all the way back to 91' --Chad--
 
how much does it bump it up? I have an auto, but when I'm using my OBA (sanden) I sometimes wedge something in the throttle linkage to hold the idle high and it pumps faster. I think I'm gonna just do the bike shifter hand throttle that will click and stay at different increments.
 
a little over 1k rpm
 
They are numbered on the connector... this is for the 99-01 atleast, I am still trying to figure out how far back the wire is the same color and in the same place.

edit:
just looked at your info and see you have a 2001...just pull off the connector from the PCM, you'll see the #'s...then release the 4 legs that clip the rear cover of the connector to the main plug, you will see the wire corresponding to the right location... this is needed since the black plug has two gray wires in it... one of which is a tachometer wire, grounding this wire will surely make problems for the PCM...it's likely to atleast stumble if not shut off completely...
 
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old_man said:
It is real easy. Find the pressure switch on the power steering pump. All you have to do is short across the switch. The function of the switch is to bump the idle if you turn the wheel all the way to one side and stall the power steering pump. If the idle wasn't bumped, the engine would die. It is also connected to the AC compressor switch so if the compressor kicks in at an idle, it wouldn't die.

It's a nice mod especially if you have a manual tranny. No big help if you have an auto.

I'm almost certain my 91 4.0L HO does not have any pressure switch on the PS pump. Can some one verify this? Also, Pin 10 (PS switch) on the ECU...well mine has no wire there. Any other pins that will do the same?
 
Anything more come of this for the 00/01's. I have been thinking of trying it, but I'm not 100% if the switch compleats the ground path, or provides 12V to pin #12. The way it looks on my FSM it switches 12V. Can anyone confirm this?
 
stoneattic said:
Talk to ghettocruiser on here. He's using a cruise control (I believe) to raise his idle when his York OBA is running.
Yes I've heard of that, but the newer XJ's have a high idle control right in the ECU. I was just wondering if anyone tried using it yet. All I would need is a switch to eather ground the cicuit, or supply 12V. I'm just not shure which.


EDIT: Nevermind I just looked over the schematic again, and see that it completes the ground path. It parallels the power steering pressure switch circuit
 
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I have an 01 and the had the high idle GROUNDED switch for over a year with no problems. In fact it has been on since October. Helps when warming up.

Hans
 
Ok... not sure if I'm getting all this..

for a pre 90 xj put 12v to D2 on the ECU? and what is D2 used for the AC?

I would like to try this also for my OBA

thanks,
Bob
 
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