Chevrolet Repair Questions? Ask a Mechanic for Answers ASAP
hi, let me check a few things here and I will get back to you shortly ...jazzmaster ..
do you have good grounds from the motor to the frame/body ?
no, the pcm is more for the injectors and idle etc .,the spark is more controlled by the dist /coil
do you have battery voltage at the coil with the key on -pink wire
do you have battery voltage on the pink wire at the dist with the key on >?
are these newer spark plug wires ?
do you have hot spark from the coil to the dist cap ?
is it hot at the dist --coil wire or is the spark weak all around
do you want to talk via the phone ,it cost a little more but we can be direct instead of back and forth -I think its around $10 ,but we can continue here anyways ..
is the voltage pulsating a little on the pink wire at the dist when it is being cranked over .or the white wire
ANd I know you got a new dist but has the ignition module been changed ?
does your truck have a tach/rpm gauge in the dash ?
and if it does ,is it moving when you crank it over ?
and you said you changed the pcm ?
can you see if you have a rpm with the white wire at the coil or with a scanner ?
did you by chance check the fuses ?
if not check all of them .
I say this because there may be fuses that are blown that you didn't know about ..
at the ecm/pcm check at terminals -F15 and E 15 these should show bat voltage in the run or start position -pink wires
at -E 16 -orange wire this will be hot at all times .....
you have all the grounds and hots injector pulse but weak spark from the coil and I assume the voltage isn't pulsing like it should from the coil ,this and no tach/rpm this points to the ecm or prom .
you tried another ecm ?
same number on the proms ?
was the used prom the same numbers ?
yeah, that is what I thought ...
The numbers have to match I would think this is the issue .but it may be that the ecm is bad as well.if you tried the prom in a different ecm and it still had the same issue then it points to the prom ,esp. if you dont have any rpm signal ..thank you ..jazzmaster ..
do you still have the used ecm ?
good first try the original ecm ,then the rebuilt ecm.
also, disconnect the timing wire -tan/black and see if it starts or has better spark -this takes the ecm out of the starting system ...jazzmaster ..
this does have a new dist and ignition module cap and rotor and this had weak spark even before all that ?
have you tried and disconnected the timing wire _brown and tan and seen what the spark looked like then ?
wow ,let me look further into this ,this is weird as you have the powers and grounds to the ecm .and you have 12 volts or so, on the coil ...
when you are cranking the motor over does the voltage on the pink wire stay the same ?
ok, does it pulsate from around 9.5 volts or so ?
ok, please let me know
you are very welcome ,in the meantime I will explore this further ,I did have a site where they explained the whole process of this circuit ,...jazzmaster ..
the ignition module should be checked anyways .
the reason I say this ,is because even though the part is new ,it still may be bad .please get that checked and see if it is good .
I have been fooled more than a few times by thinking the new parts were good and I kept going round and round trying to fix something when the issue was the new parts ..
and the symptons appeared to be the same ..thanks ..jazzmaster ..
you should be able to send that on these posts by hitting the paper clip icon ...how did you have the test light hooked up ?