Check engine and airbag isuzu trooper indicate from time to time

engine runs perfect. no misfiring at all?>??????
the computer dont know,
all it knows, is a reading fails.
in electroncs we do more testing
it can be bad wires. bad connections or bad sensors.
we use a voltmeter do check this, or a scope if fast moving signal.
1991 2.8L

"Electronic Spark Timing Circuit
Specific to 1992-93 models only.
Indicates that the ECM believes the Ignition Module has failed.
Check the wires and connectors between the Distributor and the ECM."

google finds top anwser here
https://www.2carpros.com/questions/isuzu-trooper-1992-isuzu-trooper-code-42--2

best answer ive ever seen, and for old cars, had to find,
most folks long forgot ..24 years ago
and books long ago in land fill....

if a gas engine, check spark.
if spark is good try test fuel
if test fuel fails, its compression test time.
1,2,3
watch scotty, ?
https://www.youtube.com/watch?v=064Ilsz8Fzg&NR=1&feature=fvwp

As in airbag light? Or disconnect airbag?

indicates a fuel supply and pressure problem
check and bleed the system
have the injectors professionally overhauled by a diesel specialist shop

When is the last time a tune up was performed on the vehicle? I would get some amsoil engine foam, and use it as described. Also get some fuel system cleaner and use that as well and go from there.
Thank you,
Lee

The cam pulley notch goes in line with the mark on the front cam bearing cap and the crankshaft pulley goes at 12 o'clock - its got a tiny mark on the back lip that lines up with the mark on the cover .

Did you take the cams off in one lump or split them ? if you did come back on here for how to time them up .

your computer has a code

have a 1999 3.0td trooper. Diesel fuel in coolant and overheating. Suspected problem with head so replaced with new head and gasket set. Timing appears correct.Fuel appears to be flowing. Engine will not start..turns over..no nasty noises...appears to have compression...any ideas please??

need a injector pump dial indicator to set up lift in pump (movement on dial indicator)0.05mm at correct timing mark on crank pulley 12 deg.
the above is an example for 4JB1 & 4JB1-TC
which are isuzu diesel engines

Check the battery first