Fried ECM
How do you know it's "fried?" There's a few other things it could be including a simple wiring connection failure. I HAVE EVEN FOUND two systems where there was a bad connection in one of the ECM pins in that big connector.
MAKE CERTAIN the ECU is grounded. MUST
Here's a post I made about the simplest way I know to get across testing the ECU/ ignition parts
You need a coil, the ECU and the distributor
Lay it out on the bench. Follow the diagram. Find the two distributor pickup terminals on the ECU. Hook them to the distributor
Hook the ECU case to battery NEG
Coil does NOT need grounded
Distributor does NOT need grounded.
Hook coil + to the power lead terminal on the ECU. Get a clip lead hooked there and let dangle. This is your battery "hot" when you are ready
Hook something from coil "case" to a probe for testing spark.
Hook up your power clip lead. Twist the distributor shaft while holding the test probe near the coil tower. The thing should make sparks
If not, unhook distributor. Take first one, then the other pickup clip leads, and "tap tap" ground them at the battery connection. Coil should make 1 spark each time you do so.
If not, try another coil. If that does not fix it replace the ECU
IF you hook it all up and it WORKS, then there is something AFU in the car harness. SUSPECT a bad ECU connector OR a bad DISTRIBUTOR connector
=============================================
This is all you need to test the basics of the ignition. You can easily test the ballast separate. A battery, the ECU, distributor and a coil, and of course some test leads
(copy image location......................)
Below, the basic diagram for a 4 pin ECU
Below, the wire for testing spark. I use my 12V test light. No, LOL the spark won't blow up the bulb
Below, the ground connection. ALL you need is one wire from batt NEG to the ECU case
Below, the two distributor connections. In the car these are polarity sensitive, but for testing does not matter
Below, the coil NEG connection
Below, battery PLUS connection, one wire to this terminal of ECU and jumpered over to + side of coil
Below, all hooked up and ready to test (except for battery ground). Should produce sparks at least 3/8" and typically 1/2" long
Below, distributor "one wire" test. I have removed the other distributor wire for simplicity. Take the bare connector end or this clip lead (the yellow) and with everything hooked up, ground it repeatedly. Each grounding should result in a spark (In this photo you need to hook up the ECU ground wire, I left it off for the photo)
Some generalities
Suspect the distributor pickup connector. This is prone to bad connections and corrosion.. Remove ALL connectors and inspect them with a light for corrosion, and "work" them in/ out several times to scrub the terminals and to "feel" for tightness
Inspect the distributor for reluctor strike damage, shaft wobble and bushing looseness, and for debri and rust on the pickup or reluctor
Hook you meter, when set to LOW AC volts to the distributor connector and crank the engine. Distributor should generate about 1v AC
With the key in "run" take the disconnected engine harness end of the distributor connector. Tap the exposed end on ground. Should generate a nice hot single "snap" spark from the coil each time
DO NOT check spark with a resistor coil wire. "Rig" a test gap such as a store bought tester, or an over-gapped plug, with a solid core wire. System should generate at least 3/8 nice hot blue spark and typically more like 1/2" long
Measure coil+ voltage when in "run" and when in cranking. Should have AT LEAST 10.5V in crank
MAKE SURE ECU box is grounded. FOR SURE
Don't assume the ECU (or any other connector) is "good." I have found others have found, a poor connection at the ECU. THAT IS ONE REASON WHY in the test suggestions above, I USE CLIP LEADS to test
How do you know it's "fried?" There's a few other things it could be including a simple wiring connection failure. I HAVE EVEN FOUND two systems where there was a bad connection in one of the ECM pins in that big connector.
MAKE CERTAIN the ECU is grounded. MUST
Here's a post I made about the simplest way I know to get across testing the ECU/ ignition parts
You need a coil, the ECU and the distributor
Lay it out on the bench. Follow the diagram. Find the two distributor pickup terminals on the ECU. Hook them to the distributor
Hook the ECU case to battery NEG
Coil does NOT need grounded
Distributor does NOT need grounded.
Hook coil + to the power lead terminal on the ECU. Get a clip lead hooked there and let dangle. This is your battery "hot" when you are ready
Hook something from coil "case" to a probe for testing spark.
Hook up your power clip lead. Twist the distributor shaft while holding the test probe near the coil tower. The thing should make sparks
If not, unhook distributor. Take first one, then the other pickup clip leads, and "tap tap" ground them at the battery connection. Coil should make 1 spark each time you do so.
If not, try another coil. If that does not fix it replace the ECU
IF you hook it all up and it WORKS, then there is something AFU in the car harness. SUSPECT a bad ECU connector OR a bad DISTRIBUTOR connector
=============================================
This is all you need to test the basics of the ignition. You can easily test the ballast separate. A battery, the ECU, distributor and a coil, and of course some test leads
(copy image location......................)
Below, the basic diagram for a 4 pin ECU
Below, the wire for testing spark. I use my 12V test light. No, LOL the spark won't blow up the bulb
Below, the ground connection. ALL you need is one wire from batt NEG to the ECU case
Below, the two distributor connections. In the car these are polarity sensitive, but for testing does not matter
Below, the coil NEG connection
Below, battery PLUS connection, one wire to this terminal of ECU and jumpered over to + side of coil
Below, all hooked up and ready to test (except for battery ground). Should produce sparks at least 3/8" and typically 1/2" long
Below, distributor "one wire" test. I have removed the other distributor wire for simplicity. Take the bare connector end or this clip lead (the yellow) and with everything hooked up, ground it repeatedly. Each grounding should result in a spark (In this photo you need to hook up the ECU ground wire, I left it off for the photo)
Some generalities
Suspect the distributor pickup connector. This is prone to bad connections and corrosion.. Remove ALL connectors and inspect them with a light for corrosion, and "work" them in/ out several times to scrub the terminals and to "feel" for tightness
Inspect the distributor for reluctor strike damage, shaft wobble and bushing looseness, and for debri and rust on the pickup or reluctor
Hook you meter, when set to LOW AC volts to the distributor connector and crank the engine. Distributor should generate about 1v AC
With the key in "run" take the disconnected engine harness end of the distributor connector. Tap the exposed end on ground. Should generate a nice hot single "snap" spark from the coil each time
DO NOT check spark with a resistor coil wire. "Rig" a test gap such as a store bought tester, or an over-gapped plug, with a solid core wire. System should generate at least 3/8 nice hot blue spark and typically more like 1/2" long
Measure coil+ voltage when in "run" and when in cranking. Should have AT LEAST 10.5V in crank
MAKE SURE ECU box is grounded. FOR SURE
Don't assume the ECU (or any other connector) is "good." I have found others have found, a poor connection at the ECU. THAT IS ONE REASON WHY in the test suggestions above, I USE CLIP LEADS to test
