Coil signal?
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CF Beginner
Joined: Mar 2007
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Coil signal?
I've got an 88 k1500 that just shut off while I was driving almost like it was out of gas but it wasn't. I pulled the air filter and looked in the throttle body while someone else cranked it. Fuel was being injected just fine, so I put a timing light on the main wire to the distributor. No current. So I replaced the coil. Still nothing. I inspected the connectors going to the coil and checked for voltage on each of the 4 wires. They were all hot. Now what I don't know is what the 4 wires should be doing because their states don't change at all when it's being cranked. I thought maybe 1 or 2 should go low or even pulse to activate the coil. I have a wiring diagram for the truck and that doesn't really help. 2 of the wires are pink and the other 2 are white. Can anybody shed some light? Otherwise, I'm looking at just replacing the computer to see if that fixes it.
CF Junior Member
Joined: Jan 2008
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RE: Coil signal?
Your problem is most likely the ESC module in the distributor. At least one of the white wires if not both should pulsate high low voltage. This module is about 35$ from napa. Give it a shot this sounds like your problem.
CF Junior Member
Joined: Dec 2007
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RE: Coil signal?
ORIGINAL: drmoeder
I've got an 88 k1500 that just shut off while I was driving almost like it was out of gas but it wasn't. I pulled the air filter and looked in the throttle body while someone else cranked it. Fuel was being injected just fine, so I put a timing light on the main wire to the distributor. No current. So I replaced the coil. Still nothing. I inspected the connectors going to the coil and checked for voltage on each of the 4 wires. They were all hot. Now what I don't know is what the 4 wires should be doing because their states don't change at all when it's being cranked. I thought maybe 1 or 2 should go low or even pulse to activate the coil. I have a wiring diagram for the truck and that doesn't really help. 2 of the wires are pink and the other 2 are white. Can anybody shed some light? Otherwise, I'm looking at just replacing the computer to see if that fixes it.
I've got an 88 k1500 that just shut off while I was driving almost like it was out of gas but it wasn't. I pulled the air filter and looked in the throttle body while someone else cranked it. Fuel was being injected just fine, so I put a timing light on the main wire to the distributor. No current. So I replaced the coil. Still nothing. I inspected the connectors going to the coil and checked for voltage on each of the 4 wires. They were all hot. Now what I don't know is what the 4 wires should be doing because their states don't change at all when it's being cranked. I thought maybe 1 or 2 should go low or even pulse to activate the coil. I have a wiring diagram for the truck and that doesn't really help. 2 of the wires are pink and the other 2 are white. Can anybody shed some light? Otherwise, I'm looking at just replacing the computer to see if that fixes it.
I'm not sure how you checked for a pulse reading? If your dmm has a tach setting--dwell setting---dutycycle setting, any of these will give a reading, if there is a pulse. If your just looking at voltage, I don't think that will work unless the meter has a min/max feature. If the meter averages the pulse reading then the voltage would be half compared to the B+ circuit, but the reading wouldn't pulse.
I looked up the ignition module in a parts book, it shows two connectors. The two wire connector, the wires are pink and white. The pink wire is B+ and the white wire is a tach signal. The wires at the coil may be the same.
I agree with the other person, if there is no pulse, check the ignition module or pick-up coil.
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