His response
"There are many fault codes
mass air flow
failure to connect with pcm
Ambient Air temp circuit open
Which all of those codes that are coming up could be from malfunctioning ecm"
3 ideas ( because I can not remember how to spell ‘thoughts’ )
1- marginal battery.
2- bad engine/body grounds
3- green crusties in the common harness that connects all this on top of the engine.
Remember, these are OLD machines. Wiring is always suspect and needs to be examined carefully. Not just like ‘ it looks good’. Give each wire a little tug. You may be surprised when one comes apart in your hand.
Grounds (and missing grounds) always cause electrical gremlins on these jeeps.
Just for fun - if you have a set of jumper cables, try a cable from the negative of the battery and attach the other end to the engine block. That ensures a good ground. Clear your codes and see what you get. Also go negative to body ground. Now both alternatives are covered.
You just might ‘cure’ your problem.
IMO - too many shops rely just on the scan tool and chase codes.
The CRD - I am not familiar with as far as locations of these components. But it is fairly obvious that the ECM/ PCM can not see the Air temp sensor. Is that because the ECM is bad? Are we missing a ground signal? Are we missing reference voltage?
One needs to be skilled / familiar with a multimeter / power probe and chew this up one bite at a time.
.
