bobworkman
Junior Member
- Joined
- Jul 14, 2015
- Posts
- 8
- Reaction score
- 0
- Location
- Manitoba
- First Name
- Bob
- Truck Year
- 1982, 1986 & 1989
- Truck Model
- 2 suburban C10 & C20 pickup
- Engine Size
- 305 & 350
Need some help with crank no start problem.
Vehicle is a 2WD 1986 Suburban 305 with a carb.
The ignition control module is a 5 pin version.
So I have:
verified power at dist cap B+
early test showed no blink at Tach terminal.
Multimeter probe of coil tests OK for both primary and secondary coils.
Multimeter probe of pickup coil tests OK.
This seems to say Ignition Control Module, and I have a replacement, but
I always like to confirm things.
I found a post on NastyZ28's site on how to bench test a 4 pin ICM
and articles on how to bypass the Electronic Spark Timing on several sites.
I set-up the test, 9v across B+ and ground, test light between B+ and tach,
jumper wire to B+ so I can apply momentary power to the 3 pin side.
I find that I get a flash on test light only when I apply a brief voltage
to the D terminal of the ICM (black wire).
While on a 4 pin this should happen when the green wire is temporarily given power.
Of course when I bypass the EST I get the flash when either Black and Green is
momentarily given power.
So my concern is... "is this behaviour normal" for a 5 pin module implying that
my module is OK and implying that the problem is in the EST?
Looking for my thermal paste... then a reassembly and test,
probably cap off center button test 1st.
Vehicle is a 2WD 1986 Suburban 305 with a carb.
The ignition control module is a 5 pin version.
So I have:
verified power at dist cap B+
early test showed no blink at Tach terminal.
Multimeter probe of coil tests OK for both primary and secondary coils.
Multimeter probe of pickup coil tests OK.
This seems to say Ignition Control Module, and I have a replacement, but
I always like to confirm things.
I found a post on NastyZ28's site on how to bench test a 4 pin ICM
and articles on how to bypass the Electronic Spark Timing on several sites.
I set-up the test, 9v across B+ and ground, test light between B+ and tach,
jumper wire to B+ so I can apply momentary power to the 3 pin side.
I find that I get a flash on test light only when I apply a brief voltage
to the D terminal of the ICM (black wire).
While on a 4 pin this should happen when the green wire is temporarily given power.
Of course when I bypass the EST I get the flash when either Black and Green is
momentarily given power.
So my concern is... "is this behaviour normal" for a 5 pin module implying that
my module is OK and implying that the problem is in the EST?
Looking for my thermal paste... then a reassembly and test,
probably cap off center button test 1st.