Auto gearbox and 1st gear

[Steve F]

Hi All,

I was wondering if the auto box in a cherokee will hold 1st if you place it in the 1st/2nd position and run in low range or will it change up to second. The reason I ask is I want to know what it will do on a steep decent, can it change up and run down hill in second rather than staying in 1st

Cheers
Steve

[Just Jeepin]

When I have gone downhills...it uses low gear 1st and just keeps it on there...until I found some hills where it kicks it to 2nd

The hill down to Dingo Dell is what struck me as what would kick up to 2nd but didn't...

Just happily stayed in low 1st...

Maybe some of the others may have more technical insights to this...

[Steve]

I always put it in first myself and leave it there until I am ready for it to shift. Just to be sure!

[Gojeep]

Wont shift up unless you reach the red line. Keep it below that and you should be fine.
The only thing I didn't like is that you can not lock it into second. Not all hills need 1st and if you brake a bit for a wash away it will suddenly shift into first throwing you forward against the belts. I fitted a first gear lock out switch that stopped that. tongue.gif

[OzJeeper]

M8t's

It is possible to lock the AW4 trans into 1st and 2nd with a set of mods.
I have just been looking for the particular page on Jeepin.com that I printed out Sept 2000 on a lock out type mod. Pity the page has "expired".

However - in general terms - Jeff Ayres found a way of wiring the AW4 tranny to hold 1st and 2nd on their own. Remember, it's only electrickery that decides what gear you'r in. The mod will enable you to switch in and out of holding gear.

To quote "My 2nd gear mod uses the fact that when the shift handle is in the 1/2 position, Sol1 is energised automatically and 12V is switched to the C8 input of the TCU. I am tapping off C8 for power to run Sol2 through a switch. In this manner my switch will only have power running to it if the shift selector is in the 1/2 position. Therefore, if I am in 3 or D positions and accidently operate the switch, Sol2 will not be energised and the tranny will not do any gear shifting."

The article is over 3 pages and has detailed wiring diagrams.
Lucky I printed it hey!

So all those running the XJ AW4 trranny can in fact modify it to "hold gear".

This is as far as I know - never having run or owned an XJ. Marcus may have some feedback here and if needed I will scan/post the entire printed thing FYI....

back to you....

[Bogged]

There is a company in the states that makes a module to lock in either 1 or 2. Compushift i think it is. Haven't seen it out here. It should only change down to 1st if you exceed 40/50kmh and should change up around 50kmh.

Colin
graemlins/rock.gif

[Gojeep]

This mod works for all AW4's but if you have 97 and later it will trip the check engine light every time you use it and stay on for 50 key off on cycles!
Guys have rigged up a complete gear changing setup for every gear and torque converter lock up for any gear as well. Good for down hill holding. The only problem is that the lock was not designed to be driven by the trans and like the Nissans which had a kit as well, trans failures started to happen.
The compushift was a rip off as it was the same thing as the switch idea except that it was contained in a plastic box and worked with your trans power comfort switch.
Some people have fried the TCU playing with it but I have not had any problems so you are warned.
I used the diagram from here. http://ilovejeeps.com/tech/article.cfm?ID=5

[Steve F]

Thanks for the insight guys. OZJeeper, if you do get a chance I'd like to see that article.

Cheers
Steve