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97+ cherokee extended idle


JeepcoMJ
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alright, so referencing this thread from naxja on extended idle:

http://www.naxja.org/forum/showthread.php?t=79549

 

I can NOT get any info on what would need to be done to a 5 speed ecu to get the high idle to work.

 

I'd like to make the high idle work in my '98 xj. I'd like it to appear stock. i would NOT like to use a hand throttle...that is just redneck. redneck is NOT something I'm interested in.

 

 

talking with the gurus on naxja, they can't come up with a straight answer for me.

 

 

so. here's what I've discovered.

 

 

The '97+ 5 speed and auto ECU's are the same, save some programming. they have the same amount of pins (to the extent that I can discover), share the same ecu plugs, and are the same size and "bolt pattern".

 

 

from that, I then went to deduce that some wires are in fact NOT present in the 5 speed harness, that are present in the auto harness.

 

 

I need to discover a way to trick the ecu into thinking it's in "park" or "neutral" so that I can make pin number 12 on the ECU do what it is supposed to when it is grounded out.

 

 

does anyone know of any way or have any ideas on how to go about doing that?

 

Thanks,

 

Pat

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Just throwing out a random idea. Is there any way you could adapt the NSS and associated harness to your 5spd harness? If so, would that even accomplish what you are after?

 

A few years ago I remember reading about some electronic doo-hicky you could add to the existing harness that would allow you to bump up the idle on the +03 TJs. There was quite abit of discussion about it on rubicon owners forum. I do not remember what it was called, but seems if you could adapt the system to your XJ you could simply use the Ext Idle switch as the trigger.

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Just throwing out a random idea. Is there any way you could adapt the NSS and associated harness to your 5spd harness? If so, would that even accomplish what you are after?

 

A few years ago I remember reading about some electronic doo-hicky you could add to the existing harness that would allow you to bump up the idle on the +03 TJs. There was quite abit of discussion about it on rubicon owners forum. I do not remember what it was called, but seems if you could adapt the system to your XJ you could simply use the Ext Idle switch as the trigger.

 

 

that is the general idea.

 

I actually don't need the NSS...I just need to figure out which pins to the ECU are for the NSS, and basically loop them or put a switch inbetween them.

 

the 5 speed NSS is part of the clutch master cylinder in '97+, and there is a factory bypass wire tied to the connector for it...but that doesn't solve the problem.

 

 

Unfortunately, my biggest issue is knowing whether using the auto NSS pins will even work...if the ECU will even register it, since it's flashed for a 5 speed.

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I'm sure you've read over these posts. I played with this once awhile back, but there's no provision for it on the 91 4.0 ECU.

 

http://www.naxja.org/forum/showthread.php?t=35197&highlight=extended+idle

 

http://www.naxja.org/forum/showthread.php?t=77285

 

It should be easy enough to figure out though w. a 97+ electrical FSM. You know pin 12 of the PCM needs to be grounded, along with the signal from the NSS telling the PCM that it's in PARK or NEUTRAL. The 97+ FSM should tell you which PCM pin(s) the ground or 12V signal is applied by the NSS when in PARK or NEUTRAL, right? Do you have the FSM? Once you know the pinouts, you could apply all the signals to the ECU w. a double (or triple if necessary) pole switch at the same time. Only way to find out if it will work is to try it............

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I'm sure you've read over these posts. I played with this once awhile back, but there's no provision for it on the 91 4.0 ECU.

 

http://www.naxja.org/forum/showthread.php?t=35197&highlight=extended+idle

 

http://www.naxja.org/forum/showthread.php?t=77285

 

It should be easy enough to figure out though w. a 97+ electrical FSM. You know pin 12 of the PCM needs to be grounded, along with the signal from the NSS telling the PCM that it's in PARK or NEUTRAL. The 97+ FSM should tell you which PCM pin(s) the ground or 12V signal is applied by the NSS when in PARK or NEUTRAL, right? Do you have the FSM? Once you know the pinouts, you could apply all the signals to the ECU w. a double (or triple if necessary) pole switch at the same time. Only way to find out if it will work is to try it............

 

 

 

See, that is what I'm looking for when I ask for help. you've confirmed my thought pattern on this. unfortunately, I don't have an FSM for it...I do have one for the older body style...my dad had it before '97, so it doesn't have the information needed.

 

I'll have to pick up a copy, or download it.

 

And I agree with you on using one switch with several poles to control the function at one time. I have one in mind, which is a momentary single throw...it has two inputs, two outputs, which are not connected to each other, plus a 3rd input and output for the light. it's a similar rocker design to ARB air switches...out of a peterbuilt. obviously it's electrical rather than air, and while it is a momentary switch, it does lock in to position when pushed and lock out when pushed again.

 

 

Anywho...I will have to get the FSM, figure out which pins do what, and then see if those pins even exist on a 5 speed ECU.

 

 

Thanks Don

 

-Pat

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Anywho...I will have to get the FSM, figure out which pins do what, and then see if those pins even exist on a 5 speed ECU.

 

 

Thanks Don

 

-Pat

 

They do exist on the 5speed ECU.....in fact every pin does, even ones not connected to anything....

 

Weather or not the PCM printed gel circuit board connects to them.....thats another question entirely.(though I would bet is does).

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CHER008a.png

i know that's in the link you posted, but for ease of reference...

 

you shouldn't need to do anything else besides provide ground to pin A12 (gray wire), and you shouldn't have to worry about the NSS at all. I looked at every wiring diagram involving the transmission range sensor (NSS) and the pcm as well as trans control modules, and there's no link between the two. if you want, just test it by grounding the A12 pin while it's running and see if the idle goes up. that test would cost you nothing but a couple minutes really.

 

edit: i was wrong, i missed the diagram needed. see my next post below :oops:

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i guess i'm unclear then. have you tried grounding pin 12, or read where someone else did and it didn't work? as for pin 6, that diagram shows that a6 is always grounded on the manual and grounded when the range switch is in park/neutral, so un-grounding it wouldn't help.

 

the only other link i can find in the diagrams i've found so far is the CCD bus. i know the diagnostic block doesn't do anything related to the extended idle, but it might also transfer data to and from the trans module and pcm.

 

of course, there's still the possibility that the pcm needs different programing to allow for the extended idle.

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All you need is a brick to set on the gas pedal. :thumbsup:

 

 

 

Just screwing with you Pat. :cheers:

 

 

lol...sure... :rotf:

 

I actually may have a solution that will essentially do just that, paul...

 

 

power door lock actuator mounted with a cable in the dash to the gas pedal. flip switch, turns on relay, pulls gas pedal as far as the actuator can move.

 

 

problem with this is that the actuator would probably burn out really quickly, and also get very warm, potentially starting a fire.

 

maybe then the other thing is that it's got to be able to move further than that, if need be. it's a dillema.

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yeah. I'd have supply power or ground out the a/c wire then...but I like my working a/c lol.

 

I *could* cut the wire on the back of the heater control, and use a 3 pole switch that is normally open in the "off" position, and normally closed in the "on position" so that I can retain a/c control under normal conditions, and pop up the idle under abnormal conditions.

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