87 Dodge Caravan distributor test help needed please.

Nov 24, 2006 20 Replies

My son has an 87 Dodge Caravan 3.0 auto and the spark up and quit.



The old coil was cracked with low ohm readings so we replaced it just because.



The coil is getting power, but it is not getting the negative pulse to fire it so there is no spark coming out.



I have a good multimeter and need to know how to test the output from the distributor optical pickup unit. I figure I should be able to maybe read voltage pulses on one of the wires or use the ohm meter on it but have no idea what the pinout should be.



Any help would be appreciated seeing as the part costs $300.29 freaking dollars! (more than the van cost)



Thanks,



Mike



86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
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First thing would make sure the dist is turning when the engine cranks. How many miles on the timing belt? Is it showing any codes? If so post back code no.

Here is a volt/ohm meter test for it.

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us know how it goes. MT

Distributor is turning.

I 'think' it has a timing chain? No matter, mileage unknown on either.

If it has slipped a tooth anywhere, I would still have spark out of the new coil I would think.

Mike

The 3.0 has belt. But if dist is turning you should have spark.

We went back to it and got the codes. We have 12, 11, 54 and 55 or end of codes in that order.

There is no alternator or oil light on the dash lit up, but don't know if there ever was. All it has is the power lit that displays the codes.

We just found the test for the optical sender and have your link for the SMEC so will go with those. Dark out now and son has to go to work so tomorrow for the testing.

Thanks for the help.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Bingo on code 54. Run this test on it.

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us know how it goes.MT

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Nope, the Mitsushitti 3.0 has a rubber band.

Definitely.

Ok, ran the tests. The distributor failed code 54 or the sync was bad. Replaced the pickup.

We cleared the codes and now only have code 12 and 55.

New coil. Checks out for primary and secondary resistance.

Power pulse to coil when ignition is turned to run and steady power of

10.8 Volts when key is in start with starter turning. 8 volts or so evident on the negative side. Steady though.

Jumpered coil to battery power. Fuel pump was heard pumping, but still no spark when turned over.

Replacement from a runner of the distributor. Have voltage input and outputs on correct lines from pickup. No codes for the distributor now. Have continuity to ground on the distributor ground wire.

Coil suppression wire verified for continuity with 7K ohms. Replaced with meter probe wire to check for spark against the engine. No spark for either.

Tried a boost just in case the battery was too low to fire up computer. No real difference, it is a new battery well charged.

There is a small gas smell now.

I am now thinking the computer up and died...?

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Classic symptom of a failed body ground... did you check that braided wire between the engine and body? Bob

Possible. It might just be flooded. Try swapping the plugs.

That was rather wry, Bob. Not that I'm complaining...

: )

Toyota MDT in MO

No spark and the body ground was jumpered with a booster cable.

Mike

I checked the ground strap and it is physically in place. My son mentioned he used a booster cable from the battery negative to the body before he got a hold of me to check for that.

Mike

Even if flooded I would think it would have a spark coming out of the coil....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Connect a test light between coil negative and ground.

Key on, does it light?

Crank engine, does it flash or stay steady?

My meter implies the coil gets one pulse of power when the key comes on. It sees 10.8 volts on the positive side when cranking.

The negative side of the coil sees 8 volts when cranking and the 8 appears steady to me. I am going back over to it with a logic probe test light so I can see for sure, but the other signal lines (out of the distributor) that pulsed appeared as an unsteady middle voltage on the meter. (supposed to be a 5 volt pulse that meter shows as 2.6 to 2.85 pulsing volts.)

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
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Connect a test light between coil negative and ground. Key on, does it light? Crank engine, does it flash or stay steady?

Meter reading are neat and all that, but I have no way of telling whether the coil negative is actually being switched on and off. The meter -could be giving an average reading depending on the type of meter and its response capabilities.

The test light, while low tech, is a better indicator.

Thanks for the help, it was the computer.

My meter is fast enough to see the pulses on the negative as it turns out so the steady reading I 'thought' I had on the negative with the dead computer was correct.

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00 88 Cherokee 235 BFG AT's Canadian Off Road Trips Photos: Non members can still view! Jan/06
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