Ignition help needed (stumped)
- Thread starter DCDuster75
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67Dart273
Well-Known Member
First step to help you narrow down is determine what exactly (if anything) does and does not work. I know what I think about part of what you said, but the oil light confuses---because it "should not work" either
In any case I would start with the bulkhead connector itself and I THINK there is more than one fuse link in that car.
You were talking about the red wire. If there is NO power at the interior of the car, that is for sure a problem right in the connector itself. IF you look at the connector, you can see latches where the sections come apart
One problem you have is that because it's a later model, there are no free service manuals available. Go to MyMopar and there is a somewhat wiring diagram, but these leave out some details (of connectors and options) and may not show "everything"
I may have a poor quality copy of the wiring. You need to look around the www and find a CD/DVD or paper reprint of the shop manual
In any case I would start with the bulkhead connector itself and I THINK there is more than one fuse link in that car.
You were talking about the red wire. If there is NO power at the interior of the car, that is for sure a problem right in the connector itself. IF you look at the connector, you can see latches where the sections come apart
One problem you have is that because it's a later model, there are no free service manuals available. Go to MyMopar and there is a somewhat wiring diagram, but these leave out some details (of connectors and options) and may not show "everything"
I may have a poor quality copy of the wiring. You need to look around the www and find a CD/DVD or paper reprint of the shop manual
DCDuster75
Active Member
Yes, i have had that apart, if you mean the connector on the red wire that looks like a fuse connector but its not? Cleaned it up as it's like a plug connector. Seems good there. Should i drop the steering column and pull the dash? Have a poke around in there or just pull out bulkhead connector first? Thanks for the reply
Professor Fate
Push the button, Max...
Sounds like a fusible link or bad connection at the bulkhead; but after that you've gotta get a (real) FSM and start tracing wires, like 67Dart273 said.
1975 PLYMOUTH DUSTER 5.2L 318cid V8 Repair Manual | RockAuto
1975 PLYMOUTH DUSTER 5.2L 318cid V8 Repair Manual | RockAuto
DCDuster75
Active Member
Sry, the connector is on the black wire coming out of bulkhead connector. My bad
67Dart273
Well-Known Member
EDIT this is not correct: The ONE advantage you have over your late model over us with "older" ones is that you do not have what we call a "full current" ammeter. This means the bulkhead connector is under less strain
Above is not correct, it was 76 that the external shunt ammeter was used
Also look for and check other fuse links. These always have an obvious bulge "for no reason" and or a molded tag hanging out to the side.
Checking fuses.......don't just look at them. Some of the fuses are hot all the time, some are hot only when the key is in "run" or "accessory." And one fuse, the INST fuse, is only hot when the light switch is "on" but ignore that one for now
To check fuses, get power TO them and check at the fuse with a light/ meter. Then apply a load such as tail lights heater whatever is on that fuse, and make certain you have power at both ends of the fuse clips
For these tests, a test lamp is often better/ easier than a meter
Above is not correct, it was 76 that the external shunt ammeter was used
Also look for and check other fuse links. These always have an obvious bulge "for no reason" and or a molded tag hanging out to the side.
Checking fuses.......don't just look at them. Some of the fuses are hot all the time, some are hot only when the key is in "run" or "accessory." And one fuse, the INST fuse, is only hot when the light switch is "on" but ignore that one for now
To check fuses, get power TO them and check at the fuse with a light/ meter. Then apply a load such as tail lights heater whatever is on that fuse, and make certain you have power at both ends of the fuse clips
For these tests, a test lamp is often better/ easier than a meter
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DCDuster75
Active Member
Thanks, yeah i have the dash out, been probing like mad, theres power to the dash main power in but zero power to fuse block . I have all sorts of test lights and digital so good there. Wiring not my strong point mechanical much much better.
DCDuster75
Active Member
Thank you very much!
Check the fusible link. It may have one at the bulkhead connector and/or coming off the starter relay next to the battery. If that checks out, check the plug where the column plugs in. Look for melted connector on the yellow wire.
Just going to add a few suggestions.
Be real careful when probeing under the dash or pulling the instrument panel out. The wires connected to the battery positive can be accidently grounded and then there will be sparks and within a second or two the fusible link will melt.
When you can, describe he wire by more than insulation color if you can. Size, what it does or the connection point, all can help.
I'll come back to this in a second post.
Note what options the car came with. In particular, if the car came with a rear window electric defrost grid, it probably has the 65 amp alternator wiring.
1975 model year may have/probably has a seatbelt interlock. Thats probably why the previous owner hacked the iignition.
See the posts later in this threadContinuing to track down source of no voltage to coil while cranking by @Bugman and @67Dart273
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DCDuster75
Active Member
Ya thought of seatbelt but attached pics. No power to fuse block power to dash panel, power comung in from bulkhead only in 1 spot thats shown from outside fuse link too. And not sure what the cylindrical relay is there i put a pic of as well. Just perplexed
Lets step back to look at the basic wiring concept.
There's a welded splice which joined the alternator and the battery with the main feeds to the key switch, lights, fusebox hot, and sometimes horn. Regardless of where power came from, battery or alternator, it went where needed from the main splice.
The fuse box has 2 - 3 fuses that get power only when the key is on, and 2-3 that are always hot.
Above I wrote "a welded splice which joined" in past tense. That's because '75 is a little different.
Also if the car had rear window defrost its again a little different.
There's a welded splice which joined the alternator and the battery with the main feeds to the key switch, lights, fusebox hot, and sometimes horn. Regardless of where power came from, battery or alternator, it went where needed from the main splice.
The fuse box has 2 - 3 fuses that get power only when the key is on, and 2-3 that are always hot.
Above I wrote "a welded splice which joined" in past tense. That's because '75 is a little different.
Also if the car had rear window defrost its again a little different.
I'm going to say this.
A. it would be best if you stopped poking holes in the insulation. Better at this point to disconnect the battery and use a continuity or resistance between connectors. If that's not an option, OK, just be careful.
This could be a grommet for main power.
If so, the car ahas the option 65 amp wiring.
If the sheet metal cuts through the insulation and causes a major spark show it won't be good.
A. it would be best if you stopped poking holes in the insulation. Better at this point to disconnect the battery and use a continuity or resistance between connectors. If that's not an option, OK, just be careful.
This could be a grommet for main power.
If so, the car ahas the option 65 amp wiring.
If the sheet metal cuts through the insulation and causes a major spark show it won't be good.
DCDuster75
Active Member
No rear defrost, thanks for the diagram
Ok. It still may have the optional 65 amp wiring. So keep that in mind.
Lets look at the '75 wiring diagram. You can then convert it or redraw into layout showing just what you are interested in. That's basically what I did above with the '72.
Here's a section of the '75. As I mentioned above, power distribution is a little changed from earlier cars.
Notice on the alternator's output wire (R6) there is a J1 wire spliced in. 12 is 12 gage
J1 typically designates a feed to the key switch. This arrangement is different from earlier wiring.
CE2 is the bulkhead multi-connector. There's a seperate drawing or list indicating which cavity.
But we can see the grsay& red fusible link should plug into one of those cavities.
In the diagram you can see the firewall grommet that we've seen cars that have had the rear defrost and 65 amp alternator wiring.
Once your sure the car does not have the 65 amp wiring option, simply ignore or erase those lines. It makes the drawings easier to read.
C13 12 black is the feed wire to rear window defrost. So we can do that right now.
Lets look at the '75 wiring diagram. You can then convert it or redraw into layout showing just what you are interested in. That's basically what I did above with the '72.
Here's a section of the '75. As I mentioned above, power distribution is a little changed from earlier cars.
Notice on the alternator's output wire (R6) there is a J1 wire spliced in. 12 is 12 gage
J1 typically designates a feed to the key switch. This arrangement is different from earlier wiring.
CE2 is the bulkhead multi-connector. There's a seperate drawing or list indicating which cavity.
But we can see the grsay& red fusible link should plug into one of those cavities.
In the diagram you can see the firewall grommet that we've seen cars that have had the rear defrost and 65 amp alternator wiring.
Once your sure the car does not have the 65 amp wiring option, simply ignore or erase those lines. It makes the drawings easier to read.
C13 12 black is the feed wire to rear window defrost. So we can do that right now.
So here's that information used to alter the schematic
So now we can see how its possible to have power at the ammeter and the fusebox, but not at the key switch.
12 gage Red with white trace is Q3 feeding the two fuses on the accessory side of the fuse box.
Black 12 gage wire is hot only when the key is turned to run or accessory.
So now we can see how its possible to have power at the ammeter and the fusebox, but not at the key switch.
12 gage Red with white trace is Q3 feeding the two fuses on the accessory side of the fuse box.
Black 12 gage wire is hot only when the key is turned to run or accessory.
If there are two ring terminals that go on the second ammeter post, then that plu the grommet with heavy red and black wire are good clues the car has the optional alternator wiring.
67Dart273
Well-Known Member
The big red wire through the grommet into the interior seems to be the battery "going in" and that seems to be the optional 65A alternator commonly known as "fleet/police/taxi" wiring. This was a modification to the ammeter circuit and normally was improved. If you have it there and not at the fuse panel, you need to disconnect the battery, drop the column, and pull the inst. cluster so you can "get in there." What you are looking at is the main ammeter circuit. The red wire feeds in direct to the ammeter, the black comes off to the welded splice, and the welded splice splits off back out to the ammeter, to the ignition siwtch, and to the fuse panel "hot" buss. NONE OF THAT is fused except for the fuse link Here is a simplified diagram from the Mad Electrical
The main difference with yours is that the RED goes through a separate grommet for the 65A alternator as mentioned
What you want to do is access the ammeter terminals and check for battery power at the fuse panel "hot" buss the main feed into the ignition, the headlight switch, and out at the ammeter stud. If some of those have power but one/ some do not, it has to be in that welded splice. It of course could be the ammeter terminals or wire ends if NONE has power
The main difference with yours is that the RED goes through a separate grommet for the 65A alternator as mentioned
What you want to do is access the ammeter terminals and check for battery power at the fuse panel "hot" buss the main feed into the ignition, the headlight switch, and out at the ammeter stud. If some of those have power but one/ some do not, it has to be in that welded splice. It of course could be the ammeter terminals or wire ends if NONE has power
Bugman
Well-Known Member
1975
Bugman
Well-Known Member
Two Fuse links, ignition feed has own link
Bugman
Well-Known Member
J1 12R ignition feed circuit
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