Where is the ECU located on my 93 318 IS info on replacing the ecu car is a 1993 318 IS 4 cel at

Does your CEL not come on at all on initial start? What about with the key turned to "on" & engine off?

Your CEL comes on as part of the vehicle computer's self test. During that self test, the ECU grounds the lamp to illuminate the bulb and after the test is complete, ground is removed and the light turns off.

When that light doesn't come on at initial startup, there could be a problem with the lamp's circuit leading to/from the ECU or the driver in the ECU that grounds it is defective. The CEL pin in the ECU should be tested for continuity and grounded externally (such as with a test light) to make sure it illuminates. IF it does light up, there's an issue with the ECU.

to fast hot and too fast cold that it?
well here is normal, its a G16 engine, a Vitara with Sidekick badge.
G16 in cold weather, start and race idle at about 1500 rpm
or more if in ALASKA, you never said that or how cold it is.
the IAC valve is thermal, it and opens more colder, a fact.
the 8valve engine (black steel top) is faster. cold idle
then drops in a few seconds, to 1500rpm
at this time, the ECU brain does NOT control idle speeds at all.
the the engine warms up by virtue of the thermostat
as it warms to 150F to on way to 180f stock temp.
the ECU then takes control of the idle speeds.
got that so far?
so at 180f the idle is 800 rpm (800 is hard coded in the ECU,
ad ECU regulates this, unless you turn on the A.C , and if that happens 1000rpm is called up.
if not the ECU cant control it or the ECU is in limphome mode or worse.

if you insert the diagnostic jumper
does the CEL lamp flash 12s
it must.
see this paper clip this is your only scan tool.
it is crude but that is all you get until 1996.

http://www.fixkick.com/CEL/CEL.html#OBD1codes

wow, no jeep stated. nor what year, nor what engine.

ill not even beg country (exports are diffr)

below is all ways, discounting bulb tests.



i guess you mean the key on only self test fails with CEL?

ok the PCM glows the lamp at key on, to tell you the PCM is happy and that it passes its rudimentry self checks

basically means its alive.

if the lamp fails to glow ? (all ways, i fix ECU so know this)

1. power to lamp dead (fuse ) yes fuses can crack (unseen)



2. lamp bad, (test it with a battery)



3. cluster wiring to lamp bad, or that wire from PCM to lamp bad.



4. ECU bad, yes, some bad ECU's can run an engine.



5. ECU stuck in backup mode, (think limphome but 2 times worse)

in your case id say bad ECU, or bad wire from ECU to CEL.



no year stated, so is it 1988 with that silly junk RENIX EFI with no working CEL or is the unstated car 1993+ where the CEL started working for the first time?

if 93 or newer, we can connect a scan tool, and scan it.

and see , omg , comms are dead, so ECU is in backup mode.

(backup mode is like lawn mower mode, sure it runs but like crap)

ask? can give vivid details of all modes.....



or comm's is ok, and scans and we see DTCs stored and the CEL status in the scanner says ON,"aka, active CEL"



if it says ON< and is not on, then the wire is bad or the

CEL transistor in the ECU blew up. (common with folks using wrong bulb and overheating this poor transistor) replaced many i have.



there are some facts. and is poorly stated. due to NO YEAR !



retired, ET,

This could be something as simple as the Service Engine Soon light bulb being burned out. Removing the instrument cluster isn't too terribly difficult, but if you can carefully pull it out of the dash, look behind where the bulbs are located and see if that one happens to be burned out.
I hope this helps! :)

might be as simple as a blown dash bulb

blown fuse.
the CEL lamp must glow, or the ECU is dead. (no power)
the CEL is very important lamp telling you the ECU has power
and it thinks(sic) that it is ok, (basics)
if the lamp is burned out, it become hard to work the ECU.
as this ECU flashes codes for errors,
check all fuse. in both boxes.

fix overheating first.

but on some cars, (all really) the cooling system can be MARGINAL.

eg; RAD tubes clogged.

and you dont know that.

then the ECU gets in an uproar, and sets DTCs and the CEL glows

and is now in limphome mode (is cel glowing running?)

so in limphome , the spark timing is way retarded dumping a huge

heat load on the water jackets, and now overheats

in limp home the sparks gurn black it misfires and overheats.

all early ,90s. cars did this, in 1996 its way less, many mech, never seen this cuz never see 90s cars, 88 is first ive seen. that can do this. carbs dont. before.



step 1: (do that skipped 60k tune up,now, SURE)

check all fuse.

step 2, is the CEL lamp glowing key on, no fix that because

The ecu has an ever more dumb mode,called BACKUP

backup the CEL goes DEAD and HUGE heat load. and black smoke.

step 3, CEL glows, i run engine and its still glowing

insert the diagnostic jumper (paper clip works easy) and get the FLASHING error codes. now.

use a scan tool to reset the ECM

you need to get the code checked from the ecu using an OBDII scanner, otherwise the information you have given cannot be used to diagnose the problem.

The check engine light comes on if any of the car's sensor's are faulty or do not respond to the ecu.

If the car drives perfectly even though the light comes on, the likely problem is the o2 (lambda) sensor on the header or cat, which causes a CEL but no ill running effects.

Go to a garage who can pull the codes off the ecu then look up the code on the integra or honda forums and take it from there.

i can solve this, im a sidekick expert.

if your car is federal car (not calif) it has a SES lamp mileage nag.
this nag can come on at 50k, 80k and 100k and repeats.
here is my web page just to solve this issues. guaranteed to be good.

http://carfix.stufftoread.com/CEL/CEL.html