gsboone

When I disconnected battery terminals to clean up I lost the programming for the computer, so car would not pass smog later in the day. If I disconnect negative cable to battery for starter replacement, will I lose programming again on 96 Cherokee 4.0?

dcollins3208

Yes, you'll need to drive anywhere from 30-100 miles for your sensors to checkout as "ready." Some vehicles require several warmup cycles to pass

Garrett S.

Probably. I don't think it matters what cable is disconnected it looses it when the battery is unhooked.

jordan96xj

First the 96 computer is not very sophisticated. There are several emissions related checks done by the computer that must be in the "Ready" state before an emissions test can be performed. When the computer is without power, it comes back online with a code that lets the computer know that it has been reset. A certain regiment of drive cycles must occur before the emissions checks will return to the "Ready" status.

If you get a $25 BAFX OBD2 bluetooth scanner, it will show you the Ready/Not Ready status of the emissions system checks.

The following article gives a better description of the emission monitor checks, and the drive cycles required to bring them back into a ready state:

http://www.smogtips.com/smog-questio...tors-Not-Ready

(They don't specify whether they are talking about a classic Cherokee or a new one, but the concept is the same).

fb97xj1

You likely failed because the emissions monitor readiness test was incomplete, and therefore, no data for the shops computer to evaluate. The PCM has to complete a drive cycle or two. I forget how long that usually takes but until then, Gandalf says you shall not pass.

The PCM goes thru a learning curve everytime you disconnect the battery.

gsboone

Thanks, folks. I found everyones input as useful. I see I can buy "memory keepers" for keeping power to computer, etc. in a few simple ways, but unless someone is trying to pass smog in a hurry, it just isn't that big of a deal. Plus, I can change out the starter, after the smog test. It still works, just tight.

BlueRidgeMark

[QUOTE=gsboone;3385780]... unless someone is trying to pass smog in a hurry, it just isn't that big of a deal. /QUOTE]

Eggstackly.