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Hello, I have a 2005 grand caravan with the 3.3l v6. dead miss on cylinders 1 and 4. I back probed the coil connector signal wires to see if the firing
signals were there, all good except for the 1/4 tower. That should mean open circuit in the wiring or bad driver in the ECM. Correct? At this time i decided to send it to the local shop as it was dark outside and since i wasn't feeling well (covid 19 strikes again!). My wife picked up the van and they told her it had a bad coil pack! can the coil pack itself cause the signal from the ECM to not show up. Thanks for the help!
Hey Scott1969! How exactly were you measuring the 1/4 coil signal at the coil pack? DMM, test light?
How the coil pack failed (if indeed the coil pack is the problem, and the only problem) will make a difference as to how it shows up in your testing. For example, if the 1/4 primary winding in the coil pack was electrically open, then it'll potentially change test light behavior.
Gotcha. So, to confirm, if you take your test light connected to B+ and touch a backprobe installed in the 1/4 coil control circuit with the engine running, the light does not pulse? Or, does the light stay on solid?
Hello, The test light wasn't lit at all. I should have used a multimeter which would have shown me ghost voltage and i would have known there was an open primary winding. When i used the test light, it was connected to B- with no lighting of the bulb. But it would flash on the signal wires for the remaining good coils. Also i forgot to mention the test light was incandescent not led.
When i used the test light, it was connected to B- with no lighting of the bulb.
That test told you either the primary was open/high resistance or the control was shorted to ground. Then switch the test light to B+ and if it flashes control is good. Lights up solid control is shorted.
Voltage checks with a DMM isn't a good test for primary circuits. A high resistance coil will test good and most of them ain't fast enough to check for control.
That test told you either the primary was open/high resistance or the control was shorted to ground. Then switch the test light to B+ and if it flashes control is good. Lights up solid control is shorted.
Voltage checks with a DMM isn't a good test for primary circuits. A high resistance coil will test good and most of them ain't fast enough to check for control.
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