shift light **5 SPEEDS READ**

[PhotographerMike]

I think the shift light is just there for entertainment value.

I don't see how it would help you save gas. Mine tends to comes on at low RPM's with light throttle and go off when I speed up and hold that higher speed.

On cars sold in California in 1996, the light was disabled so the car could meet CA. emission standards better by not telling you when to shift.

My '96 is a 4 cylinder, so it has 4.11 gears = 3000 RPM @ 70 which gets tiresome. (And no, I won't trade.)

 

[jeepcomj]

the 4.0 powerband is right around 2300RPM. this is where it gets it's best economy and power, regardless of gears.

so, run it between 1900 and 2300 RPM. no lower at cruise, and shifting should be around 2500 RPM.

you honestly can't feel it bog your engine down? you should be able to just tap the gas slightly to get it to go. if you have to stomp the gas to the floor to see results, get in a lower gear.

 

[jeepcomj]

I think the shift light is just there for entertainment value.

I don't see how it would help you save gas. Mine tends to comes on at low RPM's with light throttle and go off when I speed up and hold that higher speed.

On cars sold in California in 1996, the light was disabled so the car could meet CA. emission standards better by not telling you when to shift.

My '96 is a 4 cylinder, so it has 4.11 gears = 3000 RPM @ 70 which gets tiresome. (And no, I won't trade.)

advice, run your 4 cylinder between 3000 and 3400 RPM as that's where IT'S powerband is.

you won't be disapointed.

 

[Jarvis_Pants]

WOW what fun is having 4.0 if you have to mudle around at 2500 rpm. In my auto XJ i love cruseing along and slamming my foot down it shifts down not 1 but 2 gears and weeeeeeeeee good bye. maybe one of the reasons im having to rebuild my engine.

 

[vetteboy]

the 4.0 powerband is right around 2300RPM. this is where it gets it's best economy and power, regardless of gears.

so, run it between 1900 and 2300 RPM. no lower at cruise, and shifting should be around 2500 RPM.

It's actually higher than that. Mid to high 2k range.

Renix ones are a little lower.

 

[jeepcomj]

It's actually higher than that. Mid to high 2k range.

Renix ones are a little lower.

agreed. sorry, i didn't take the HO into consideration as I play with comanches...it's hard to find a 91-92 comanche

 

[RichP]

Avtually I think that shift light is based of vacum not rpm or speed or throttle position, no it's not vac fed but I think the computer triggers it based on it's vac readings. It actually behaves like a vac shift gauge when you think about it.

 

[vetteboy]

Avtually I think that shift light is based of vacum not rpm or speed or throttle position, no it's not vac fed but I think the computer triggers it based on it's vac readings. It actually behaves like a vac shift gauge when you think about it.

Yep, it is. I said that in post #6 but apparently no one else read it either.

:looney:

 

[PhotographerMike]

Advice, run your 4 cylinder between 3000 and 3400 RPM as that's where IT'S powerband is.

you won't be disapointed.

Agreed, but at 3000 all the vibrations come together, engine, tires, hatch and everything else that can shake.

Speed up to 3200 and everything quiets down but I'm going 75+ and trying to push a "brick" through the air.

Around town 3300+ is definately where it's at with the 4.11's.

Mike

P.S. and the shift light never comes on . . .

 

[tgoff]

The shift light is hooked up to the transmission and is called an upshift lamp switch Part Number 5300 2831 at least on my '86 2.5L AX-5 model. When I did my AX-15 swap(http://www.naxja.org/forum/showthread.php?t=956031) it no longer had the 2 prong hookup on the transmission.

 

[emr1101]

It's actually higher than that. Mid to high 2k range.

Renix ones are a little lower.

Cool I appreciat that, and Jeepcomj for the original post...

Looks like I'll try that, ive always heard it and i know its easier to drive that way just never could figure out if it was better fuel economy. I understand my gears are off, which is why im trying to figure this all out. I like many of you dont have a $1000 laying around for some 4.10s but i wish i ddid. Ill try to keep it around the 2500-3000k sweet spot. Thanks a lot guys for all your insight!!!!

 

[XJ_ranger]

I usually shift when I stop going faster because the rev limiter is cutting spark...

ignore the light, re-gear, keep ignoreing the light...

 

[emr1101]

Hey for those of you with 5 speeds and a stock shift light, is the shift light dependant on your RPM and gear? or your SPEED and gear?

its kind of stupid like ill be doing a pretty decent speed and wont really need a whole lot more power and ill be in 3rd gear but it wont tell me to shift, itll keep me in 3rd while i could save like 300 RPMs by going into 4th and yet still have the same momentum (3rd and 4th are retarded 3rd is way to high its like freaking same as 4th)..... then as far as 1st and 2nd go itll tell me to shift before i even hit 2000rpm, wtf? i mean that might be okay but whys it telling me to wait to shift out of 3rd untill 2k? thats just stupid do they thikn the regualr speed limit is like 60? most states its 45.

I guess im just trying to figure out optimum shift points given my gears (3.07s on 32s... soon to be 33s).... At first i thought the lower the RPM the better because its rotating the engine less, thus firing the pistons less, but if the engine is almost bogging or at like 1200 rpm maybe its putting more stress on the engine so its dumping more fuel in and increasing compression? Kinda like how you can floor it and nothing will happen, the butterfly valve on the throttle body is wide open - but is it adding more fuel to the mix as well?

Anyway, i just asked like 5 different questions lol so if you could try to help me out with as many as possible! Any advice or help would be appreciated!:cheers:

haha well looks like i was right all along, earlier i shift better mileage i get. i spent a tank of gas shifting (like oyu guys said) at like 2500-3000ish (depending on who said it) and althogh 3000rpm may be the most EFFICIENT stage for power-per-fuel ratio, its not the lowest (fuel cunsumption). Anyway, i got 13mpgs versus 16 i got when i shifted right at 2000. Sooooo I think Im gonna stick with shifting how i always have!

 

[xjbubba]

The shift light is hooked up to the transmission and is called an upshift lamp switch Part Number 5300 2831 at least on my '86 2.5L AX-5 model. When I did my AX-15 swap(http://www.naxja.org/forum/showthread.php?t=956031) it no longer had the 2 prong hookup on the transmission.

Huh? Off the tranny? Don't think so. At least not with the 4.0. My Peugeot 5-speed had a 2-prong connector that "told" the back-up lights when to come on.

The Renix ECM controls the shift light. Wire comes out of ECM connector B8 and goes directly to the IP.

My current Chevy engine/ECM combo also has the same up-shift feature. It's only used with the manual tranny, however; autos don't use it.

The Chevy light is about as functional as the Renix light; ignore it!

 

[XJ98Jeep]

My shift light is AWFUL. It tries to tell me to upshift at a ridiculously low RPM like 1200 RPM, and it never comes at on a reasonable RPM like 2000-5250RPM. Only ridiculous RPMs.

 

[emr1101]

mine tells me at like 1900-2200 it seems, pretty decent

 

[tgoff]

Huh? Off the tranny? Don't think so. At least not with the 4.0. My Peugeot 5-speed had a 2-prong connector that "told" the back-up lights when to come on.

The Renix ECM controls the shift light. Wire comes out of ECM connector B8 and goes directly to the IP.

My current Chevy engine/ECM combo also has the same up-shift feature. It's only used with the manual tranny, however; autos don't use it.

The Chevy light is about as functional as the Renix light; ignore it!

My AX-5 had the reverse switch as well as the up shift light as explained previously with the OEM part number I gave. I wish I have taken a pic but that transmission is in the trash where is belongs. The reverse switch from the AX-15 plugged into my AX-5 harness end switch so my reverse lights work fine since my swap but since the AX-15 did not have the switch my up shift lamp no longer works and I have a connector hanging off of my harness with nothing to connect it to. I could take a pic of this if needed. I looked up the Peugeot application and it does not have the switch on the transmission like you said and unlike the AX-5. It appears the switch on the transmission is unique to the AX-5 equipped XJ's.

Here is the page out of the Jeep Parts Catalog