I have been reading all the threads about the charging systems on the Mark 7's. I recently bought a used 86 mark 7 and it needs some work, but just a bunch of little stuff really, but I started with the charging system first because I have to get it first or the rest is irrelevant. I have had the alt checked and it puts out 14.69V. I changed the regulator and have checked all the wiring to the battery. I even jumped the regulator from the A to F to make alt charge.............nothing. My question is I don't think the wires coming from the VR are telling the alt to get the field coils to turn on or it would have when I jumped it. What I'm looking for is a good schematic of the chargind system so I can see where the voltage is suppose to be and if I have to run new wires just need to know where they go so I dont have to tear the whole wiring loom apart. Sorry about the book just trying to give as much info as possible to see if you all have some ideas.
Charging Schematic
- Thread starter gramps
- Start date
OldSchool1
Dedicated LVC Member
Congratulations on the 86! If you're suffering from "crank, no run" the it could be a half dozen things.
Fire.
If you have a timing light (or can borrow one) verify spark at the wires.
Air.
Our Mark VIIs get their air (factory installed cold air intake) from the PS fender. Verify that there are no blockages from the grey milk bottle looking thing with a horn opening in the fender, to the throttle body.
Fuel.
If you have a round faced tire pressure guage (not the pocket jobbers), then verify 40# of pressure at the fuel rail with the key in the run position. The fuel rail port is the only thing in the engine bay that accepts a fuel/tire pressure guage (other than the factory air spring compressors). Lastly, our Mark VIIs need two gallows of fuel to run, and five gallons of fuel to drive.
After market alarms and switches.
Momentem switch.
Fuel pump.
Planets out of alignment.
etc.
Let us know when you've verified the first three.
Welcome.
Just charging
It will start and run, I just can't get any voltage to the battery when I turn on lights or any accessories. It acts like the VR is not gettting the signal to turn the field coils on in the alternator to make it start charging. Took the alt to Autozone and had it tested it will put out 14.69 volts. I was wanting to know what are the four wires coming into the VR so I can check how much voltage they are suppose to have at each one and where they come from. I also replaced the VR and battery. This is why I need a schematic of the charging system to see where the VR picks up when to tell the alt to start charging. I bought a haynes manual but that is the worst set of schematics I have ever came across in my 20+ years of being a mechanic. Hope this clears the air what I'm looking for.
It will start and run, I just can't get any voltage to the battery when I turn on lights or any accessories. It acts like the VR is not gettting the signal to turn the field coils on in the alternator to make it start charging. Took the alt to Autozone and had it tested it will put out 14.69 volts. I was wanting to know what are the four wires coming into the VR so I can check how much voltage they are suppose to have at each one and where they come from. I also replaced the VR and battery. This is why I need a schematic of the charging system to see where the VR picks up when to tell the alt to start charging. I bought a haynes manual but that is the worst set of schematics I have ever came across in my 20+ years of being a mechanic. Hope this clears the air what I'm looking for.
OldSchool1
Dedicated LVC Member
Yup. That's it.
I've just updated my signature to include a link to the tech article concerning our ignition switches (not key cylinders).
I misunderstood your problem.
Let us know what you find.
I've just updated my signature to include a link to the tech article concerning our ignition switches (not key cylinders).
I misunderstood your problem.
Let us know what you find.
Magic Al
LVC Member
OldSchool1
Dedicated LVC Member
With my scanner tucked away somewhere in a box, we can count on you for graphical answers.
Thanks.
Thanks.
Got it
Once I found the wiring schematic I found the problem. Actually two problems. One was the rear window defogger had an open circuit and found a broken wire going up to the starter solenoid for the charging system. Amazing how some schematic will help you identify the wires and where they are going. Replaced the wire and switch and she is putting out 14+ volts under a load. I went ahead and replaced the ignition switch while I was at it. Does anyone have a good source for getting depedable parts for these cars. I need the right door acctuator for the lock, had to diconnect the linkage to get the passenger door to open.
Once I found the wiring schematic I found the problem. Actually two problems. One was the rear window defogger had an open circuit and found a broken wire going up to the starter solenoid for the charging system. Amazing how some schematic will help you identify the wires and where they are going. Replaced the wire and switch and she is putting out 14+ volts under a load. I went ahead and replaced the ignition switch while I was at it. Does anyone have a good source for getting depedable parts for these cars. I need the right door acctuator for the lock, had to diconnect the linkage to get the passenger door to open.
OldSchool1
Dedicated LVC Member
Great.
The ignition switch is the first step into evicting gremlins.
The ignition switch is the first step into evicting gremlins.