Mechanics

NO SPARK FROM COIL

1998 Dodge Truck • 183,000 miles

We replaced the crank sensor, cam sensor, checked relays, plugged canobd2 tool into computer which read no codes and scan incomplete I have been told if you get no codes that it is the Ecm.
I also turned the ignition switch and pushed the odometer button at the same timeand it flashed 900,929,999, all fuses and relays are good. I powered the 1 side of the coil but the other would not purge
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Numberoneelkhunter
August 22, 2013.



You're going to end up frying a computer that way.

All "crank, no start" conditions are approached in the same way. Every engine requires certain functions to be able to run. Some of these functions rely on specific components to work and some components are part of more than one function so it is important to see the whole picture to be able to conclude anything about what may have failed. Also, these functions can ONLY be tested during the failure. Any other time and they will simply test good because the problem isn't present at the moment.
If you approach this in any other way, you are merely guessing and that only serves to replace unnecessary parts and wastes money.

Every engine requires spark, fuel and compression to run. That's what we have to look for.

These are the basics that need to be tested and will give us the info required to isolate a cause.

1) Test for spark at the plug end of the wire using a spark tester. If none found, check for power supply on the + terminal of the coil with the key on.

2) Test for injector pulse using a small bulb called a noid light. If none found, check for power supply at one side of the injector with the key on.

3) Use a fuel pressure gauge to test for correct fuel pressure, also noticing if the pressure holds when key is shut off.

4) If all of these things check good, then you would need to do a complete compression test.

Once you have determined which of these functions has dropped out,
you will know which system is having the problem.

Wrenchtech
Aug 22, 2013.
The plug wires have no spark, the engine shutdown relay going to the coil is good, but there is no spark to the coil or injecters

Tiny
Numberoneelkhunter
Aug 22, 2013.
OK, give me results to the rest of the testing
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Wrenchtech
Aug 22, 2013.
The crank shaft sensor is new and tests ok, the cam shaft sensor is new, rotor is new, dist. Cap new, tested power out of cm to coil and injectors as per chart and has power going in but 0 comeing out

Tiny
Numberoneelkhunter
Aug 22, 2013.

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