I'm doing the
on-off
on-off
on-off
on-off
on-off
on
thing, shown in this video to see error codes on my '89 Jeep Cherokee, but nothing happens. That is, there's no "check engine" light coming on.
Why is that? Shouldn't it normally come on?

 

No

 

its nevr going to you have a renix ecm equipped xj there is no light in the dash either

 

http://en.wikipedia.org/wiki/Renix

 

no cel on a renix.

This question comes in alot, I have a little paragraph wrote up on renix. Ill post it in a minute (gotta search for it)

 

Key on key off technique won't work on 87-90. That luxury began in 1991 and ended sometime in 1997.

With RENIX, all you can get is real time data and for that, you need specialized equipment.

If you have any symptoms, post them here in detail for comment.

 

Oh ok, thank you guys.
Just recently bought it so I'm still learning the basics since I'm new to Jeeps.

The symptoms..
It backfires (stalls?) alot at ca. 2000 rpm, worse when it's cold, but it's still there even though it's hot.
Just recently it died on me when I took my foot of the gas in order to break for a speed bump, twice in a row, but hasn't happened since.

Don't know if it's related to that, but it has happened twice, I think, that when I start it up it revs up to about 2000/2500 rpm out of nowhere.. I just turned it of and on again and that seemed to work.

What could it be?
Crank position sensor? Fuel pump?
Recently changed the fuel filter.

 

There is a CEL - it's a holdover from the GM V6-173 (which AMC bought with OBD-I control electronics.)

However, AMC-engined XJ and MJ through 1990 did not have OBD-compliant control systems - while there's a window for the CEL/MIL, there's no bulb behind it and there's no circuit to power the bulb anyhow.

Most RENIX troubleshooting can be done with a DMM and a little know-how - the RENIX FI manual is available online (I think Pirates of the Rubicon still has a copy, and I know I have one up at groups.yahoo.com/group/RENIXPower.) However, for most RENIX problems, I've been able to trace them to shonky grounds (about seven times of ten.) So, check that first.