No spark

Tiny
GREG91
  • MEMBER
  • 1997 DODGE CARAVAN
  • 6 CYL
  • FWD
  • AUTOMATIC
I have dodge caravan 97 3.0 the is thereno spark going through the plugs but there is fire in the control wires to coil is there fire there when the key switch on? Because there on fire when im cranking the engine and where can I find the tranmission control module what does it look like where is I located. Im not sure but I believe the the control wire for the coil is not sending enough power to fire the plugs or the pcm is not getting signal from crank shaft sensor.
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Monday, January 3rd, 2011 AT 2:34 AM

12 Replies

Tiny
CARADIODOC
  • EXPERT
My head is spinning. You need to use some punctuation so the sentences make sense. Also, by "fire" do you mean "voltage" or are some wires melting or overheating? There will not be any voltage to the coil unless the engine is rotating, (cranking or running).

Have you checked for fuel pressure? There are three separate but related systems. Most no-start problems are caused by the trigger circuit that turns on the ignition coil, injectors, and the fuel pump.

Caradiodoc
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Monday, January 3rd, 2011 AT 3:22 AM
Tiny
GREG91
  • MEMBER
Ok sorry yeah votage. And where do I find the trigger circuit? How do I check it/ and one more question if the timing belt was broke and I cranked the engine could have messed the heads up?
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Monday, January 3rd, 2011 AT 4:01 AM
Tiny
GREG91
  • MEMBER
And no I didnt the fuel pressure I will tomarrow.
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Monday, January 3rd, 2011 AT 4:05 AM
Tiny
GREG91
  • MEMBER
The ASD relay run those three thing but the ful pump comes on for about 5 seconds the goes off.I check the relays
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Monday, January 3rd, 2011 AT 4:38 AM
Tiny
CARADIODOC
  • EXPERT
The 3.0L is not an interference engine so the valves won't be damaged.

The trigger circuit is the optical pickup assembly in the distributor, (camshaft position sensor), and the crankshaft position sensor. He lives in the transmission housing right behind the rear cylinder head, close to the firewall. When pulses arrive from those two sensors, the Engine Computer knows the engine is rotating so it turns on the automatic shutdown relay and the fuel pump relay. The ASD relay sends voltage to the ignition coil, injectors, alternator field, and oxygen sensor heaters.

You know the fuel pump circuit is working because you can hear it run for a few seconds. The ASD relay should be turning on at the same time. Use a test light or digital voltmeter to measure the voltage on the dark green / orange wire in the connector for the ignition coil, an injector, or either of the small terminals on the back of the alternator. You should see 12 volts for one second after turning on the ignition switch. What's important is it must come back as soon as you start cranking the engine.

Caradiodoc
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Monday, January 3rd, 2011 AT 5:29 AM
Tiny
GREG91
  • MEMBER
OK I put a new crankshaft position sensor so I that works I also changed the camshaft position sensor. And yes I hear the fuel pump soon as turn the key to the on position then it stops. And so yours saying the ignition coil, injector and alternater should have 12 volts at each of them for one second rite? Then as im cranking the engine it should be 12 in each items?
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Monday, January 3rd, 2011 AT 5:57 AM
Tiny
CARADIODOC
  • EXPERT
Yup. 12 volts for one second at key-on, and 12 volts again during cranking.

Have you checked for stored diagnostic fault codes? Cycle the ignition switch 3 times from "off" to "run" within 5 seconds, then, on older cars you have to count the flashes of the Check Engine light. I think by '97 the codes are displayed in the digital odometer display. There should be a code if the Engine Computer detected the missing pulses from the cam or crank sensor.

Be aware too that a spacer is needed to set the air gap of the crankshaft position sensor. Original sensors use a thick paper spacer stuck to the end, then you push the sensor in as far as it will go. The spacer will slide off when the engine is started. You can get new ones from the dealer's parts department.

Some aftermarket sensors have a thin plastic rib molded on the end to set the gap. That rib partially wears away over time. To remove and reinstall that type of sensor you are supposed to cut the remaining rib off, then use the paper spacer.

In some cases, failure to use a spacer could cause the sensor to break from being hit by the ring on the torque converter.

Caradiodoc
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Monday, January 3rd, 2011 AT 7:14 AM
Tiny
GREG91
  • MEMBER
Ok will do. I put the dianostic code reader it p0443 something about evap proportional purge solenoid that wouldnt stop it from starting would it? And ima check that crankshaft sensor the first one took had nothing on it. And the first thing that dont have 12 volts that when I start there trace my way back
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Monday, January 3rd, 2011 AT 1:50 PM
Tiny
GREG91
  • MEMBER
Hey I mad I little progress today the timing mark was set wrong on my timing belt I fix that now it getting spark but wont start backfire threw the plenum all I did was slide cranshaft sensor up its tryna start I lined everthing up everything number 1 at tdc and the rotor button over top of number 1 plug still back firing and but wont start whats my next step?
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Tuesday, January 4th, 2011 AT 12:15 AM
Tiny
CARADIODOC
  • EXPERT
If you did that, the rotor is off by 90 degrees. If you look at the terminals under the cap, you'll see the tunnels where the conductors go to the terminals on top of the cap. They aren't straight above each other. That was done to make the plug wires look pretty by being in nice straight rows next to each other.

Caradiodoc
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Tuesday, January 4th, 2011 AT 12:42 AM
Tiny
GREG91
  • MEMBER
Ok tho I set it under number plug when I put the timing belt I put it over top of put 1 I took the distributer up and twisted the rotor to the number 1 plug does that mean she still it off by 90 degrees if that doesnt work what my next step
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Tuesday, January 4th, 2011 AT 12:57 AM
Tiny
CARADIODOC
  • EXPERT
Sorry, I don't understand what you're doing. The distributor doesn't have to be removed when replacing the timing belt. When piston 1 is at top dead center, the rotor should be pointing between the top terminals for cylinders 2 and 6. That's where the circuit comes out the inside of the cap and touches the rotor for cylinder number 1. As I recall, that will have the rotor pointing straight toward the back of the vehicle.

Caradiodoc
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Tuesday, January 4th, 2011 AT 8:08 AM

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