There is always going be some voltage drop. Depending on many factors the VD you are seeing could be quite normal, especially if electrical accessories have been added. A new harness might have the same VD...
Ignition woes
- Thread starter dartbro
- Start date
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I agree, but my wiring is 52 years old.
67Dart273
Well-Known Member
The big splice can be fixed by removing the cluster. just start at the black ammeter wire and untape the wrap and follow it down. I've forgotten "how many inches" but I'd guess 6? Maybe a bit more?
The first one of these that actually failed--and I fixed--was about 1971 or 72 in a friend's apartment parking lot in his 68 RR. The ammeter would jump and flutter like crazy. I new nothing about them, then, but had a 69 RR and had bought a factory service manual at the dealer. I had the dash harness pulled partway out and the cluster out, and my friend was beginning to wonder if his 68 would ever run again. "So did I!!!"
Since then I've been privy to maybe 6 or 8 that have failed. Failures are rare, but it DOES happen.
The first one of these that actually failed--and I fixed--was about 1971 or 72 in a friend's apartment parking lot in his 68 RR. The ammeter would jump and flutter like crazy. I new nothing about them, then, but had a 69 RR and had bought a factory service manual at the dealer. I had the dash harness pulled partway out and the cluster out, and my friend was beginning to wonder if his 68 would ever run again. "So did I!!!"
Since then I've been privy to maybe 6 or 8 that have failed. Failures are rare, but it DOES happen.
Thanks for all your help. I'm still learning. It's unusual to see someone give of their knowledge in the ways you have. I bought a shotgun, having never used one. It took me a while to understand how it operates 'mine,' and it's taking me time to grasp these concepts- current flow is needed to measure voltage drop, which varies with the current, what is a short, and backfeeding, for example.
Even though my short(s) is not fixed, I plan to leave the 3 fuses out, hook up my ignition switches at the bottom of the steering wheel and check out cranking voltage at the coil, and check the total voltage drop at the + coil in run and when cranking.
Even though my short(s) is not fixed, I plan to leave the 3 fuses out, hook up my ignition switches at the bottom of the steering wheel and check out cranking voltage at the coil, and check the total voltage drop at the + coil in run and when cranking.
Well thanks, but I don't understand why you would experiment with the ignition circuit when there is an electrical short.
To me, its like having a leak in the plumbing. The pressure and flow won't be sufficient where its needed, and its draining the battery.
Just so the others here can follow.
1970 Barracuda w/ hemi - pretty much all original.
All multi-connectors at the bulkhead disconnected.
Steering column key switch connector disconnected.
With a jumper between fusible link/relay and bulkhead feed. There's power on the switched accessory buss of the fusebox.
My suggestion is to remove the three fuses on the switched accessory buss.
The goal is to narrow down the wires and locations where the mean feed could be connecting to a switched feed.
At some point you'll have to trace harnesses and maybe even unwrap them. But if its the tail lights/ stop light circuits, then there's no point opening the harness around the mainsplice, etc etc.
Shotgun. I'm not big on youtube experts, 'cause they usually aren't. That said, Paul Harrell, while not giving instruction on you tube, has a quite a few videos on shotguns for home defense and hunting. He's not sponsered by anyone, not even pop-tarts. There's probably a few guys in the Guns, knives and dogs thread that might have some suggestions for finding some expertise local to you.
I did not know about 'shorts', and when my bulkhead connectors looked good, and the low voltage was showing up on the brown ballast resistor bypass wire under cranking, I was led to the ignition switch, thinking there was rust/resistance inside.
I did not know that the quality of lights and accessory leads as shorts within those wires, coming off the main splice could affect the Ign 2 start circuit. Also, my starter did not have bad voltage drop, grounds looked good, so I focused on the ignition switch wires under the dash. You've helped me a lot. When voltage at the ammeter connections was close to battery voltage and the same low voltage was showing up at the red J3 and Accessory connectors, I thought 'bad splice.'
I did not know that the quality of lights and accessory leads as shorts within those wires, coming off the main splice could affect the Ign 2 start circuit. Also, my starter did not have bad voltage drop, grounds looked good, so I focused on the ignition switch wires under the dash. You've helped me a lot. When voltage at the ammeter connections was close to battery voltage and the same low voltage was showing up at the red J3 and Accessory connectors, I thought 'bad splice.'
Last week you described measurents you made with the bulkhead and steering column disconnected, dome light on.
10.1 Volts measured at the fusebox hot buss (Q3 )and the steering column connector (J1)
3.7 Volts at the switched accessory connection (Q2A) in the fusebox
On Friday you were pulling fuses on the hot buss and noted
12.47 volts at Q2A-12BK with dome light and map light off.
Based on this, there is a short or maybe a backfeed, which for diagnosing can be considered a short.
Electricity is finding some path into the disconnected circuits.
With all of the steering column wires disconnected there should be no power available Q2, Q2A or any circuit that is powered through the key switch.
Remove each fuse from the switched buss to determine if the short is through one of those circuits. It would not be too surprising if it was related to the tail lights.
10.1 Volts measured at the fusebox hot buss (Q3 )and the steering column connector (J1)
3.7 Volts at the switched accessory connection (Q2A) in the fusebox
On Friday you were pulling fuses on the hot buss and noted
12.47 volts at Q2A-12BK with dome light and map light off.
Based on this, there is a short or maybe a backfeed, which for diagnosing can be considered a short.
Electricity is finding some path into the disconnected circuits.
With all of the steering column wires disconnected there should be no power available Q2, Q2A or any circuit that is powered through the key switch.
Remove each fuse from the switched buss to determine if the short is through one of those circuits. It would not be too surprising if it was related to the tail lights.
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Battery voltage before start: 12.35. Voltage at start 10.15. I have not measured voltage drop from the starter relay to the red ammeter bolt, because I noticed when starting the car, I only get 8-9 volts on my meter, but while starting, if I move the key just a tad 'up from the max downward point, I got 12.1 volts, with my key on the 'start' side of the ballast resistor. This result is strange to me, because I only got 10.15 in 'run,' with the + meter end on the 'run' side of the ballast resistor.
I read your tail light comment, and I'm by myself, so later in the week, I plan to have someone help me test this hypothesis. In the late '90s, there was a local MoPar club, but it's gone now. People I've to whom I've mentioned my problem last week just want me to take my car to a shop and get it 100 %. There is no inherent interest in the object in itself, only the sense of ego and alienation from the object itself, just the dream of bragging rights at a show, with your eye on the next step up and making profits.
I read your tail light comment, and I'm by myself, so later in the week, I plan to have someone help me test this hypothesis. In the late '90s, there was a local MoPar club, but it's gone now. People I've to whom I've mentioned my problem last week just want me to take my car to a shop and get it 100 %. There is no inherent interest in the object in itself, only the sense of ego and alienation from the object itself, just the dream of bragging rights at a show, with your eye on the next step up and making profits.
I need to recharge it. thanks.
you have helped me and being apart makes problem solving hard. I have 12.4 volts +- .2 at 5 wires at the power splice, but when I turn the ignition key to run, it drops to 10 something. I have 12.3 volts at the red battery wire going up the steering column, J1-12R. But when I turn the ignition switch to 'run,' voltage drops to 10 something. Now on the start circuit, I get the same old drop, but I noticed when turning the key all the way to start, if I let up on the switch a tiny bit, voltage goes for an instant to 12 something. I now see the effect of this low voltage in the steering column spreads throughout the whole system, when I turn the key. Also, the voltage drop test from the blue, J2A-16 DBL under the steering column is around 2.8 volts.
67Dart273
Well-Known Member
You have to follow the path. The terminals, connectors, switches in the path. The big big offenders are the terminals in the bulkhead connector, the ignition switch connector, THE SWITCH CONTACTS themselves, and less often, the ammeter terminals, and rarely, but has happened, a failure of the welded splice. This is taped up in the harness behind the cluster in the BLACK ammeter wire a few inches from the ammeter.
"Chase it." (the drop) Check where you can and make notes, maybe even draw out the diagram. See if you can probe it at the interior end of the bulkhead connector. If not, drop to the ignition switch connector. Check BOTH halves of the connector
I often recommend a "work around." If you can't or wont replace the switch (example) then cut the IGN1 wire coming out of the bulkhead into the engine bay, and add a relay. Use the cut end out of the firewall to trigger the relay, feed the relay from the start relay "big stud" and connect the other end of the cut wire to the switched load contact.
"Chase it." (the drop) Check where you can and make notes, maybe even draw out the diagram. See if you can probe it at the interior end of the bulkhead connector. If not, drop to the ignition switch connector. Check BOTH halves of the connector
I often recommend a "work around." If you can't or wont replace the switch (example) then cut the IGN1 wire coming out of the bulkhead into the engine bay, and add a relay. Use the cut end out of the firewall to trigger the relay, feed the relay from the start relay "big stud" and connect the other end of the cut wire to the switched load contact.
66jim
Well-Known Member
Check the air gap on the dist. it can cause the key switch problem you described. Don't get to caught up on the voltage drop yet. shoot 3-5 amps draw thru the coil primary. Voltage/resistance =amps. Resistance of primary windings of coil measured with ohm meter (coil disconnected) plus ballast resistor. Voltage measured at ballast. example 10.5V/ 1.4+1.1 ohms= 4.2 amps.
I've gotten a lot of help from Mattax and am waiting for a buddy to come to my house to do what you guys have mentioned.
While I had time, I stripped the cloth off the splice and got battery voltage, 12.4 to 12.6 on all 5 wires as best I could. Then when I turned the ignition switch to 'run,' I got about 9 volts on every wire, which I don't understand.
On the black fuse side I got 0, then 9 when I turned the switch.
Next I measured the resistance under my steering column, (everything I know of 'off') : red battery wire to blue run wire : 0 ohms, after turning the switch.
red battery wire to brown start wire: 0 ohms, after turning the switch to start.
I changed the ignition switch long time ago with Mattax when he explained
I needed a load, instead of hooking up directly to a car battery. With this switch
today I got 1.6 ohms, perhaps reflecting my error in frying it.
Brown start wire at steering column to brown ballast resistor wire at 'start': .6 ohms
Blue run wire steering column to blue ballast resistor wire with key at 'run': .6
ohms.
I know what Mattax said about load and voltage drop, but I just wanted to look at resistance. I did find a rear window defroster had been turned on when Mattax was helping. sorry, I thought a neighbor was running a blower. Getting at the splice made me unloosen wires from being tightly wound over the years. When I hooked everything up, the voltage at the ballast resistor under run was 10, so maybe I'm OK up to that point.
While I had time, I stripped the cloth off the splice and got battery voltage, 12.4 to 12.6 on all 5 wires as best I could. Then when I turned the ignition switch to 'run,' I got about 9 volts on every wire, which I don't understand.
On the black fuse side I got 0, then 9 when I turned the switch.
Next I measured the resistance under my steering column, (everything I know of 'off') : red battery wire to blue run wire : 0 ohms, after turning the switch.
red battery wire to brown start wire: 0 ohms, after turning the switch to start.
I changed the ignition switch long time ago with Mattax when he explained
I needed a load, instead of hooking up directly to a car battery. With this switch
today I got 1.6 ohms, perhaps reflecting my error in frying it.
Brown start wire at steering column to brown ballast resistor wire at 'start': .6 ohms
Blue run wire steering column to blue ballast resistor wire with key at 'run': .6
ohms.
I know what Mattax said about load and voltage drop, but I just wanted to look at resistance. I did find a rear window defroster had been turned on when Mattax was helping. sorry, I thought a neighbor was running a blower. Getting at the splice made me unloosen wires from being tightly wound over the years. When I hooked everything up, the voltage at the ballast resistor under run was 10, so maybe I'm OK up to that point.
How "warm" should be ballast resister be with ING 1 on just a short while, then after turning to ING2 for just a few cranks of the starter???
Following this thread as I have having new start issues , I assume this question is maybe related
!!
Following this thread as I have having new start issues , I assume this question is maybe related
!!
67Dart273
Well-Known Member
Ballast resistors run HOT!!! You likely will not be able to touch it after only a short time, and I don't even know what that is, 30 seconds? a minute? It's why they are ceramic
If wiggling the key moves readings substantially, you have likely found the problem, "right there." column switches are known for becoming warn, and then the contacts can "waltz around" in there and sometimes give "weird" results.
If the "run" position is getting flakey I've recommended to many to use a relay to run the engine bay "run" loads This also is a workaround fix for too high charging voltage, AKA voltage drop to the VR "it thinks" the battery is low and overcharges
If wiggling the key moves readings substantially, you have likely found the problem, "right there." column switches are known for becoming warn, and then the contacts can "waltz around" in there and sometimes give "weird" results.
If the "run" position is getting flakey I've recommended to many to use a relay to run the engine bay "run" loads This also is a workaround fix for too high charging voltage, AKA voltage drop to the VR "it thinks" the battery is low and overcharges
My friend came over, and disconnected the starter relay and got 10 something volts in the run and 12.4 in start circuit, so I may be OK with the under the dash wiring and a new ignition switch. I never found a short so far.
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