gm may not use one, but in my xj cherokee, it was the timing sensor that
simply screwed onto the back of the bell housing. wires from it update the
timing to fire right.
after three tow jobs, i found this and it fired up and is still ok 1 year
The tester used puts a load on the module. By the time they do the
test the third time, it's plenty hot. And since we've done that on
two seperate occasions, we're fairly certain that isn't the problem.
I checked the wiring yesterday, and it all seems to be in order. I
guess we're down to checking on the possiblity we were sold a bad
Replace the ICM, or have a tech put it on a scope and tell you for sure
what's wrong with it.
No matter how many times you check the ICM on a load tester, it won't even
come close to the conditions under the hood. ICMs are the most sensitive
ignition part to heat and vibration.
We replaced the ignition module, and it doesn't appear to have fixed
the problem. The wiring is good, everything in the distributor has
been replaced, and we have no clue what else it could be. The guy at
Napa is wondering if it could be a spark control module or the
computer. We don't think it has a SCM, and we're not 100% sure it has
a computer. Did the '84 Blazer have either? If not, what in the
world else could be wrong with this thing?
Now I'm down to buying something else to drive while I scratch my
1) It doesn't have a SCM
2) It <might> have an ECC if it's stock. Do you have a fully manual carb
or a computer controlled carb (will have idle mixture solenoid, 02 sensor,
3) Read the suggestion made in my prior post.
Here's my $0.02. Electrical connections are sensitive to heat. The hotter
the temps, the higher the resistance. This is the cause of "heat soak"
where the starter turns VERY slowly when the engine is nice and hot (say you
pull off the higway to grabe a coke, then restart and it really lugs) due to
the starter and wiring being so damn hot.
Because yours is dead only when hot, I'd start looking for wire<s> related
to the ignition system that may have made their way close to a source of
Well here's mine(.02).I had a 2.8 that did the same thing. After many
modules I bought a rebuilt distributer and that worked. My Nephew (Mr.
Goodwrench) said the aftermarket modules were not as good as they could be.
Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here.
All logos and trade names are the property of their respective owners.