77 Dodge truck ignition problems
12-12-2013, 04:24 PM
#1
New Member
Thread Starter
77 Dodge truck ignition problems
Hi all. I have a 77 Dodge club cab with a 360. I am having ignition problems and have read multiple threads on this forum trying to fix it, but no luck. This started 2 weeks ago. I drove it on a Friday and parked it in my barn. On Sunday I tried to start it, but had no spark. I could get spark from the coil when turning the key off, but no other time. Here is what I have tried and ruled out so far.
new ballast resistor
new ignition module - tried two
new pickup
coil - tried two
ignition switch -got a new one and it tested the same as the old one
continuity, voltage, and resistance tests on wiring as described on this forum and in Chilton manual
checked the connections on the back of the ammeter
new rotor - it needed one anyway
I am at a loss. This is not a complicated system and I feel like I'm missing something simple. Any ideas are greatly appreciated.
new ballast resistor
new ignition module - tried two
new pickup
coil - tried two
ignition switch -got a new one and it tested the same as the old one
continuity, voltage, and resistance tests on wiring as described on this forum and in Chilton manual
checked the connections on the back of the ammeter
new rotor - it needed one anyway
I am at a loss. This is not a complicated system and I feel like I'm missing something simple. Any ideas are greatly appreciated.
12-12-2013, 04:37 PM
#2
There are always "little tricks" that can throw you off, use your head.
One example is broken connections inside the ECU connector. You can throw parts at it for a month and not fix it.
Another is that there is nearly zero current in the distributor pickup connector. These are subject to oxidation and corrosion, something that happened to me on my old FJ-40 Landcruiser, Mopar powered
With "so much trouble" it's time to really put on your thinking cap
You can sometimes use straight pins to penetrate wiring into the connector to see if you have voltage that far. Use an ohmeter in each ECU connector position and "ohm out" each wire.
Process of elimination / substitution.........use test leads to actually wire up the system "breadboard" to test it "off the car." Biggest thing is finding a junkyard, or NAPA, to get and ECU connector, or with a bag or two of clip leads from Radio Shack, you can wire it without a connector
Remove and wiggle all connectors, "feel" for tightness, and look inside with a penlight to inspect. SCRAPE the firewall and make absolutely certain the ECU is grounded.
POWER!!!!! On most Mopars, the "run" line from the key GOES DEAD when cranking. The only power to ignition during crank is the bypass circuit. Mopar calls this "IGN2" This was traditionally a brown wire, comes off a separate contact on the IGN switch to the coil + side of the coil.
So be CERTAIN that you have voltage to the coil when cranking.
TACH.........you have one? Disconnect it!!! It's been known "rarely", for a defective tach to ground the coil and prevent triggering.
DISTRIBUTOR. Disconnect the connector, and hook your multimeter to the dist. on low AC volts. Spinning the dist. by hand, or cranking, should result in about 1V AC
Inspect the pickup/ reluctor. Make certain the dist ACTUALLY REVOLVES!!!! You might have a stripped timing gear, etc. Inspect the pickup / rotor for strike damage, debri, and rust. Check the gap at .008"....that's inches not metric, with a non magnetic feeler. O'Reallys had them in brass.
With key in "run" and distributor disconnected, you should be able to ground one of the two (forget which, try both) of the dist. connector wires and generate a spark each time.
One example is broken connections inside the ECU connector. You can throw parts at it for a month and not fix it.
Another is that there is nearly zero current in the distributor pickup connector. These are subject to oxidation and corrosion, something that happened to me on my old FJ-40 Landcruiser, Mopar powered
With "so much trouble" it's time to really put on your thinking cap
You can sometimes use straight pins to penetrate wiring into the connector to see if you have voltage that far. Use an ohmeter in each ECU connector position and "ohm out" each wire.
Process of elimination / substitution.........use test leads to actually wire up the system "breadboard" to test it "off the car." Biggest thing is finding a junkyard, or NAPA, to get and ECU connector, or with a bag or two of clip leads from Radio Shack, you can wire it without a connector
Remove and wiggle all connectors, "feel" for tightness, and look inside with a penlight to inspect. SCRAPE the firewall and make absolutely certain the ECU is grounded.
POWER!!!!! On most Mopars, the "run" line from the key GOES DEAD when cranking. The only power to ignition during crank is the bypass circuit. Mopar calls this "IGN2" This was traditionally a brown wire, comes off a separate contact on the IGN switch to the coil + side of the coil.
So be CERTAIN that you have voltage to the coil when cranking.
TACH.........you have one? Disconnect it!!! It's been known "rarely", for a defective tach to ground the coil and prevent triggering.
DISTRIBUTOR. Disconnect the connector, and hook your multimeter to the dist. on low AC volts. Spinning the dist. by hand, or cranking, should result in about 1V AC
Inspect the pickup/ reluctor. Make certain the dist ACTUALLY REVOLVES!!!! You might have a stripped timing gear, etc. Inspect the pickup / rotor for strike damage, debri, and rust. Check the gap at .008"....that's inches not metric, with a non magnetic feeler. O'Reallys had them in brass.
With key in "run" and distributor disconnected, you should be able to ground one of the two (forget which, try both) of the dist. connector wires and generate a spark each time.
Last edited by 440roadrunner; 12-12-2013 at 04:39 PM.
12-13-2013, 07:07 PM
#4
New Member
Thread Starter
Thanks for the replies. Many of those things I have already done. I finally figured it out today. When I put the pick up on, it was very cold and I couldn't feel my fingers. I had the gap set too wide. I reset it today and it runs! Thanks
11-06-2017, 12:21 PM
#5
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There are always "little tricks" that can throw you off, use your head.
One example is broken connections inside the ECU connector. You can throw parts at it for a month and not fix it.
Another is that there is nearly zero current in the distributor pickup connector. These are subject to oxidation and corrosion, something that happened to me on my old FJ-40 Landcruiser, Mopar powered
With "so much trouble" it's time to really put on your thinking cap
You can sometimes use straight pins to penetrate wiring into the connector to see if you have voltage that far. Use an ohmeter in each ECU connector position and "ohm out" each wire.
Process of elimination / substitution.........use test leads to actually wire up the system "breadboard" to test it "off the car." Biggest thing is finding a junkyard, or NAPA, to get and ECU connector, or with a bag or two of clip leads from Radio Shack, you can wire it without a connector
Remove and wiggle all connectors, "feel" for tightness, and look inside with a penlight to inspect. SCRAPE the firewall and make absolutely certain the ECU is grounded.
POWER!!!!! On most Mopars, the "run" line from the key GOES DEAD when cranking. The only power to ignition during crank is the bypass circuit. Mopar calls this "IGN2" This was traditionally a brown wire, comes off a separate contact on the IGN switch to the coil + side of the coil.
So be CERTAIN that you have voltage to the coil when cranking.
TACH.........you have one? Disconnect it!!! It's been known "rarely", for a defective tach to ground the coil and prevent triggering.
DISTRIBUTOR. Disconnect the connector, and hook your multimeter to the dist. on low AC volts. Spinning the dist. by hand, or cranking, should result in about 1V AC
Inspect the pickup/ reluctor. Make certain the dist ACTUALLY REVOLVES!!!! You might have a stripped timing gear, etc. Inspect the pickup / rotor for strike damage, debri, and rust. Check the gap at .008"....that's inches not metric, with a non magnetic feeler. O'Reallys had them in brass.
With key in "run" and distributor disconnected, you should be able to ground one of the two (forget which, try both) of the dist. connector wires and generate a spark each time.
One example is broken connections inside the ECU connector. You can throw parts at it for a month and not fix it.
Another is that there is nearly zero current in the distributor pickup connector. These are subject to oxidation and corrosion, something that happened to me on my old FJ-40 Landcruiser, Mopar powered
With "so much trouble" it's time to really put on your thinking cap
You can sometimes use straight pins to penetrate wiring into the connector to see if you have voltage that far. Use an ohmeter in each ECU connector position and "ohm out" each wire.
Process of elimination / substitution.........use test leads to actually wire up the system "breadboard" to test it "off the car." Biggest thing is finding a junkyard, or NAPA, to get and ECU connector, or with a bag or two of clip leads from Radio Shack, you can wire it without a connector
Remove and wiggle all connectors, "feel" for tightness, and look inside with a penlight to inspect. SCRAPE the firewall and make absolutely certain the ECU is grounded.
POWER!!!!! On most Mopars, the "run" line from the key GOES DEAD when cranking. The only power to ignition during crank is the bypass circuit. Mopar calls this "IGN2" This was traditionally a brown wire, comes off a separate contact on the IGN switch to the coil + side of the coil.
So be CERTAIN that you have voltage to the coil when cranking.
TACH.........you have one? Disconnect it!!! It's been known "rarely", for a defective tach to ground the coil and prevent triggering.
DISTRIBUTOR. Disconnect the connector, and hook your multimeter to the dist. on low AC volts. Spinning the dist. by hand, or cranking, should result in about 1V AC
Inspect the pickup/ reluctor. Make certain the dist ACTUALLY REVOLVES!!!! You might have a stripped timing gear, etc. Inspect the pickup / rotor for strike damage, debri, and rust. Check the gap at .008"....that's inches not metric, with a non magnetic feeler. O'Reallys had them in brass.
With key in "run" and distributor disconnected, you should be able to ground one of the two (forget which, try both) of the dist. connector wires and generate a spark each time.
11-28-2017, 07:38 AM
#6
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It should have an electronic distributor? does it have two or 4 wires coming out of the distributor? If 2 you can swap it over to a much more reliable and hotter spark GM/Ford HEI ignition for about $30 and some junkyard scrounging. I switched my slant six over a couple of months ago and am amazed at how much better and quicker it fires and runs. You will be able to bypass all the stuff that usually fails ie module and balast.
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