ignition problems
First, it may not be ignition, but rather carb/ vacuum leak
But the blue to the alternator field, one of the regulator (IGN) terminals, and the "input" side of the ballast resistor is SUPPOSED to be tied together. Refer to these simplified diagrams:
A simplified diagram of the older "5 terminal" ECU NOTE the notch in the ballast, it's important it be oriented this way:
Also, you can wire the vehicle for a 4 pin ballast and use EITHER a 4 or 5 terminal ECU. You can NOT tell by looking if an ECU is 4 or 5 pin, as some 4 pin ECU's have 4, some 5. The only way to tell for sure is to use an ohmeter on the "5th" pin to see if it's hooked up or not. If you wire for a 4 pin ballast, it does not matter which ECU
The diagrams below are meant for "conversion." Note the wire at top right marked "existing wire" which represents the dark blue (in many cars) which comes from the key through the bulkhead and is the "switched igntion" or "run" sometimes called "IGN1" by mopar
THIS POINT in the harness, labled "existing wire" is where the factory "Ys" off to the IGN (blue) terminal at the regulator and the blue field connector at the alternator, AND electric choke, if used, and I BELIEVE distributor retard and idle solenoid, if used.
WHAT IS NOT SHOWN is the (sometimes brown) "bypass" wire, which comes from a separate contact in the IGN switch, through the bulkhead, to the + side of the coil. This switch contact only does one thing---when the key is in "start" the brown is hot, and feeds hot 12V to the coil + for starting.
Wiring for a 4 pin ECU, note the 2 pin ballast
Something that is getting to be a huge problem, I write in just about every post, is VOLTAGE DROP in these old harnesses, caused by corrosion in connector or in the ignition switch. Problems are typically in various connectors, ESPECIALLY in the bulkhead connector
READ this excellent article at MAD electrical:
NOTE I don't know what changes they made in your later truck, so some of this might not apply
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
which came from here:
http://www.madelectrical.com/electrical-tech.shtml
One thing you need to get, and I don't have access to, is at the very least a wiring diagram for your vehicle and better yet a shop manual. If nothing else, you should be able to get one on CD from the eBay.
I would make some voltage checks to confirm or eliminate voltage problems in your rig.
Check voltage at the IGN supply wire coming out of the bulkhead to the "key" side of the ballast. Best way to do this is to measure voltage drop directly. To do so, set your meter on low DC volts, turn the key to "run" with the engine OFF.
Stick one probe onto the battery pos. post, and the other onto the "key" side of the ballast. You are looking for a low, very low voltage, the lower the better. If you show over .2v (two TENTHS of a volt) be concerned, try to find out why, if it's approaching or over 1/2 volt, or more, REALLY did in and find out why
First, it may not be ignition, but rather carb/ vacuum leak
But the blue to the alternator field, one of the regulator (IGN) terminals, and the "input" side of the ballast resistor is SUPPOSED to be tied together. Refer to these simplified diagrams:
A simplified diagram of the older "5 terminal" ECU NOTE the notch in the ballast, it's important it be oriented this way:
Also, you can wire the vehicle for a 4 pin ballast and use EITHER a 4 or 5 terminal ECU. You can NOT tell by looking if an ECU is 4 or 5 pin, as some 4 pin ECU's have 4, some 5. The only way to tell for sure is to use an ohmeter on the "5th" pin to see if it's hooked up or not. If you wire for a 4 pin ballast, it does not matter which ECU
The diagrams below are meant for "conversion." Note the wire at top right marked "existing wire" which represents the dark blue (in many cars) which comes from the key through the bulkhead and is the "switched igntion" or "run" sometimes called "IGN1" by mopar
THIS POINT in the harness, labled "existing wire" is where the factory "Ys" off to the IGN (blue) terminal at the regulator and the blue field connector at the alternator, AND electric choke, if used, and I BELIEVE distributor retard and idle solenoid, if used.
WHAT IS NOT SHOWN is the (sometimes brown) "bypass" wire, which comes from a separate contact in the IGN switch, through the bulkhead, to the + side of the coil. This switch contact only does one thing---when the key is in "start" the brown is hot, and feeds hot 12V to the coil + for starting.
Wiring for a 4 pin ECU, note the 2 pin ballast
Something that is getting to be a huge problem, I write in just about every post, is VOLTAGE DROP in these old harnesses, caused by corrosion in connector or in the ignition switch. Problems are typically in various connectors, ESPECIALLY in the bulkhead connector
READ this excellent article at MAD electrical:
NOTE I don't know what changes they made in your later truck, so some of this might not apply
http://www.madelectrical.com/electricaltech/amp-gauges.shtml
which came from here:
http://www.madelectrical.com/electrical-tech.shtml
One thing you need to get, and I don't have access to, is at the very least a wiring diagram for your vehicle and better yet a shop manual. If nothing else, you should be able to get one on CD from the eBay.
I would make some voltage checks to confirm or eliminate voltage problems in your rig.
Check voltage at the IGN supply wire coming out of the bulkhead to the "key" side of the ballast. Best way to do this is to measure voltage drop directly. To do so, set your meter on low DC volts, turn the key to "run" with the engine OFF.
Stick one probe onto the battery pos. post, and the other onto the "key" side of the ballast. You are looking for a low, very low voltage, the lower the better. If you show over .2v (two TENTHS of a volt) be concerned, try to find out why, if it's approaching or over 1/2 volt, or more, REALLY did in and find out why
