Battery Drain & Ecu Aggrevation

[danbyrambler]

Handy Dandy gadget/tool - - - Fixed some minor elec probs & no idea about 91 up ECU memory loss - - low idle & return to correct caused some head scratching & needless testing more than a few - - - Stumbled across this from HORNBROD

:bowdown:

 

 

On the 91-95 OBDI MJ/XJ HOs (and perhaps the OBDII system also, not sure) disconnecting the neg cable causes what I consider an issue. At rest, no IGN ON, residual memory current (microamps) is constantly fed to the OBDI ECU to retain it's open/closed loop memory. Disconnecting the neg cable causes the ECU to lose it's memory instantly. For the ECU to completely "re-learn" it's residual settings, it needs to be driven about 100 miles or so, especially on a modified engine. It's a minor PITA as the idle is always lower during the process, and sometimes causes stalling when in stop and go traffic. Preventing this loss of ECU memory is easy by hooking up a common 9VDC battery with alligator clip leads attached across the neg battery post and cable (observing correct polarity) before disconnecting the battery neg cable. A healthy 9V battery will retain the ECU's memory for days since the draw is so small while you are working an electrical problem on your rig

 

& Then

 

Found this - - - Wal Mart's got 'em - - - Google it & many other vendors - - Approx $10-12

http://www.walmart.c...Keeper/15523521

 

Hangs on shops pegboard now, right next to my favorite screwdriver

:thumbsup:

[gogmorgo]

Good to know, thanks!

[88mjgilley]

the cig plug would work due to the key needing to be on to be able to send or receive voltage you would put to much of a draw on a 9v and kill it in seconds

[skidoo_j]

the cig plug would work due to the key needing to be on to be able to send or receive voltage you would put to much of a draw on a 9v and kill it in seconds

 

*Wouldn't work*

[HOrnbrod]

Read my original post.

 

Preventing this loss of ECU memory is easy by hooking up a common 9VDC battery with alligator clip leads attached across the neg battery post and cable (observing correct polarity) before disconnecting the battery neg cable.

[danbyrambler]

Read my original post.

 

Hornbrod:

Understood - Sometime after reprogrm my radio a few I discovered my red top had the screw in type connections as well as top posts . . . So put in a neg post adapter 4 fast/convien & was happy until the gadget came along & I'm a sucker 4 gadgets of all sorts

 

 

88mj:

I think it'll work ok with IS in acc position - Worked when swapping bat in wifes Chrysler TC & am aware of 21yr dif of the 2 - - Anyway, JIC, all thats at risk is a return trip 2 Wal Mart - return the dead 9v as well - lol

:thumbsup: