Looks like I'm joining the won't start club.

On Saturday, I checked the spark by pulling the wire off the coil and putting it next to a ground, and there was plenty of white spark. So I checked the fuel pump and pressure, and it's OK, but I changed the fuel filter anyway. I had to think awhile as to why it won't start with both fuel and spark.

So, today, I went out and pulled some plugs, and they are fine. So I left one of the wires off and plugged in an extra spark plug, and grounded it while somebody cranked it over, and NO SPARK !

I thought it must be the ignition control module, because I had spark coming from the coil. I was about to remove it to take it in to get it tested, and I thought I would double check that I was getting spark from the coil. Cranked it over, now NO SPARK from the coil !

WTF ?

Anybody have the diagnostic flow for this ?

'97 4.3LV6 4DR 4WD AUTO

 

Step
Action
Values
Yes
No

1
Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?
--
Go to Step 2
Go to Powertrain On Board Diagnostic (OBD) System Check

2
Check the spark plug wires for open circuits, cracks or improper seating of terminals at the spark plugs, distributor and ignition coil before proceeding with the test.
Check spark at the plug with the J 26792 spark tester or equivalent while cranking. (If there is no spark on one wire, check a second wire). A few sparks then nothing is considered no spark.
Is adequate spark present?
--
Go to Symptoms
Go to Step 3

3
Remove the coil wire from the distributor cap.
Insert J 26792 spark tester into coil wire and clamp the tester onto a ground.
Crank the engine.
Is adequate spark present?
--
Go to Step 12
Go to Step 4

4
Measure the coil wire resistance using a DMM. The resistance should be approximately the specified value.

Is the resistance within the specified value?
1000 ohms/inch
Go to Step 5
Go to Step 30

5
Disconnect the ignition coil harness connector.
Probe the ignition coil connector terminal C with a test lamp connected to B+.
Crank the engine.
Is the test lamp flashing while cranking the engine?
--
Go to Step 7
Go to Step 6

6
Turn OFF the ignition.
Probe the ignition coil harness connector terminal C with a test lamp connected to B+.
Is the test lamp ON?
--
Go to Step 27
Go to Step 8

7
Turn ON the ignition, with the engine OFF.
Measure the terminal A voltage with a DMM connected to a ground.
Does the voltage measure above the specified value?
10.0 V
Go to Step 20
Go to Step 17

8
Turn OFF the ignition.
Disconnect the ignition control module harness connector.
Check for an open circuit between the ignition coil harness connector terminal C and the ignition control module harness connector terminal D.
Is the circuit open?
--
Go to Step 26
Go to Step 9

9
Disconnect the ignition control module harness connector.
Turn ON the ignition, with the engine OFF.
Measure the voltage on terminal A at the ignition control module harness connector with a DMM connected to a ground.
Does the voltage measure above the specified value?
10.0 V
Go to Step 10
Go to Step 18

10
Probe the ignition control module harness connector terminal C with a test lamp connected to B+.

Is the test lamp ON?
--
Go to Step 11
Go to Step 22

11
Disconnect the ignition control module harness connector.
Probe the ignition control module harness connector terminal B with a DMM set to the AC scale connected to a ground.
Crank the engine.
Observe the voltage while the engine is being cranked.
Is the voltage between the specified values?
1.0-4.0 V
Go to Step 19
Go to Step 14

12
Remove the distributor cap.
Check the cap f

 

Thanks. I’ll see what I can find with my meter.

 

I'm thinking I should first check the Crankshaft Position Sensor. I understand it's supposed to be above the crank pulley, but I can't even see it from the top. Does the radiator shroud or anything else have to be removed beforehand ?

 

Well, spark is back, but I have no idea why it quit. Everything checks out OK.

BTW, got bad info on the Crankshaft Position Sensor location. Jacked up the front and there it was bigger than @!#&$ !, but UNDER the crank pulley.

Are transmission coolers standard on the Blazers ? It has a looped tube type, not a stack.

I also discovered it has a block heater. The name PYROIL is embossed on the electrical plug. It's either a factory install or whoever did an after-market install is extremely fastidious, as the wiring enters one of the main wiring harnesses.

Another day, another discovery.

 

The only part I can answer is YES tranny coolers are standard.

 

External auxilliary coolers are not standard. The ones in the cold side radiator tank are standard, but other than that... No.

 

If you have the towing package you should have a dealer/factory installed auxillary tranny cooler.

My guess, and its stickly a guess. You didn't push the coil wire back on all the way. And for future refference. If you got spark after the coil, yet none at the plug, check your distriburator cap and rotor.

 

My Bravada came with the pre-run wiring harness and the trailer hitch. My truck has RPO Z82 - Trailering Provisions, Special Equipment, Heavy Duty which looks to be the only towing related RPO code for 2000. My Bravada also did not come with an auxillary trans cooler.

 

Yep, it's an external, but it's not a stack, just a series of looped tubing on an open frame in front of the radiator.