Car will not crank

[DMC-Ron]

Car will not crank. So far I have checked the obvious things.
1. The solenoid and starter work (I can jumper 12 volts to the solenoid input and it will turn engine over).
2. Power from the ignition switch start circuit is getting to the start inhibit relay (I can measure 12 volts at the relay socket coil connections, 85 – 86, when turning the key to engine start position). I also hear the relay clicking when it is installed and the key is turned to start.
3. Checked the relay on the work bench and the contacts close (30 – 87) when energized.
4. I have continuity from the relay socket (87) to the starter solenoid.
5. Also have good ground on solenoid (as I said I can jumper 12 volt to the solenoid and it will crank)
What I don’t have is +12 on the relay socket pin 30 when I turn the key to start. And that seems the problem. It needs +12 on 30 to send it out on pin 87 when the relay pulls in.
Here’s where I need help. There are some conflicts between the wiring schematic and the workshop manual.
Here the workshop manual seems to show pin 30 connected to N (always powered) circuit:
Workshop M.02.04 Start Cicuit Diagram.JPG
But the wire schematic is different:
Wire Schematic Start Relay 105.jpg
Here I’ve zoomed in on the start relay and it seems to show the WR ignition start wire connected to both pin 86 (relay coil) and pin 30 (I've added the relay connection numbers):
Wire Schematic Start Relay 105 Zoomed.JPG
I’ve checked continuity between pin 86 and 30 and there is none. Is the wire schematic correct? Should the WR start circuit connect to pin 30 then cascade to pin 86?

I realize the workshop schematic may be simplified for, well, simplification purposes, but most devices on the “always powered N” circuits go through a fuse. Is the workshop manual correct here and is there a fuse involved?

Any advice would be appreciated. Set me straight if my troubleshooting logic is off.

By the way, if I go by the workshop manual the only real reason for the start inhibit relay is for automatic transmissions. If that's true, couldn't I just remove the relay and jumper from 86 to 87?
Thanks, Ron

[Bitsyncmaster]

The schematic shows how early cars were wired which used solenoid power directly from the ignition switch. This wiring could cause starting problems because the high current required by the solenoid had more voltage drops with the longer wiring and could have burned the starter switch contacts.

The change that should be in your car moved the voltage for the solenoid to the blower circuit breaker and the let the key switch only need to drive the relay coil (low current).

Make sure your relay power connection on the blower breaker is not on the "LOAD" side of the breaker. If it was on the load side and your blower was on speed 4 then that could open the breaker when you try to start the car.

I try to always turn my fan (blower) to off in all my cars when I shut the engine off so there is less load when starting the car. Turning the blower to off also disconnects the AC compressor.

The relay was a start inhibit wired originally but with the wire change it now functions as the start inhibit and removing the high current load on the starter switch.

[DMC-Ron]

The schematic shows how early cars were wired which used solenoid power directly from the ignition switch. This wiring could cause starting problems because the high current required by the solenoid had more voltage drops with the longer wiring and could have burned the starter switch contacts.

The change that should be in your car moved the voltage for the solenoid to the blower circuit breaker and the let the key switch only need to drive the relay coil (low current).

Make sure your relay power connection on the blower breaker is not on the "LOAD" side of the breaker. If it was on the load side and your blower was on speed 4 then that could open the breaker when you try to start the car.

I try to always turn my fan (blower) to off in all my cars when I shut the engine off so there is less load when starting the car. Turning the blower to off also disconnects the AC compressor.

The relay was a start inhibit wired originally but with the wire change it now functions as the start inhibit and removing the high current load on the starter switch.

Fantastic! This info helps a lot. I'll look at the blower breaker tomorrow. It looks like this is breaker 202 "fan speed thermal trip" on the schematic. If the start relay (pin 30) is on the power side of the breaker, it would have no fuse protection. Did they add a fuse when they made this change?

Ron

[Bitsyncmaster]

Fantastic! This info helps a lot. I'll look at the blower breaker tomorrow. It looks like this is breaker 202 "fan speed thermal trip" on the schematic. If the start relay (pin 30) is on the power side of the breaker, it would have no fuse protection. Did they add a fuse when they made this change?

Ron

There is no fuse for the solenoid circuit. So it should be on the power side of the breaker. The solenoid takes about 10 amps and the blower on fan speed 4 takes about 25 amps with about 12 volts on the battery.

[David T]

For the 5-speed you really don't need the inhibit relay unless you ever want to add a switch to the clutch pedal like modern cars so you can't start it unless you step on the clutch. Makes sure the wires on the starter (the little ones) are on the right terminals.

[DMC-Ron]

Dave - you da MAN.
Problem sorted. Sure enough I found the power source for the start inhibit relay had popped off the blower fan auto trip. How did that happen you say? I will fess up. I had been working on cleaning up the relays and relay sockets and did not realize I bumped the wire.

Now just to express a mild rant of frustration, I am discouraged by the inconsistencies I notice between the DMC full car wiring diagram and the workshop manual diagrams. Also with the incompleteness of the diagrams where items on the wiring diagram are not identified and in the workshop manual where there may be a number beside a component but no legend. Of course I'm happy to at least have a basic schematic to help, without which it would be nearly impossible. It just that it could have been done better. Some of this may just be because I'm new and don't know where to find addendum information for changes and technical updates. For example, are there different versions of the full car wiring diagram to reflect the different changes from early to later cars? Rant over.

In any event, I feel very lucky to be on this forum and have access to folks who have figured out all the various quirks and nuances.

Thanks,
Ron

[Jonathan]

Dave - you da MAN.
Problem sorted. Sure enough I found the power source for the start inhibit relay had popped off the blower fan auto trip. How did that happen you say? I will fess up. I had been working on cleaning up the relays and relay sockets and did not realize I bumped the wire.

Now just to express a mild rant of frustration, I am discouraged by the inconsistencies I notice between the DMC full car wiring diagram and the workshop manual diagrams. Also with the incompleteness of the diagrams where items on the wiring diagram are not identified and in the workshop manual where there may be a number beside a component but no legend. Of course I'm happy to at least have a basic schematic to help, without which it would be nearly impossible. It just that it could have been done better. Some of this may just be because I'm new and don't know where to find addendum information for changes and technical updates. For example, are there different versions of the full car wiring diagram to reflect the different changes from early to later cars? Rant over.

In any event, I feel very lucky to be on this forum and have access to folks who have figured out all the various quirks and nuances.

Thanks,
Ron

Glad you figured it out, Ron.

There is/was a secondary file that went with the original black and white wiring diagram and it was a legend for the wiring colours and components. Do you have that file? I can see if I can find it somewhere.

Figuring the car out can be the easy part. Figuring out all the various quirks and nuances of us folks on the forum here, now that's the tricky part!

[David T]

Glad you figured it out, Ron.

There is/was a secondary file that went with the original black and white wiring diagram and it was a legend for the wiring colours and components. Do you have that file? I can see if I can find it somewhere.

Figuring the car out can be the easy part. Figuring out all the various quirks and nuances of us folks on the forum here, now that's the tricky part!

There are several versions of the starter circuit. There are a lot of inconsistencies in the documentation for the wiring. For instance there is no reference at all for the ballast relay bypass. Some of this you just have to figure out. In many cases it was among the last things you touched as in your case.

[DMC-Ron]

There are several versions of the starter circuit. There are a lot of inconsistencies in the documentation for the wiring. For instance there is no reference at all for the ballast relay bypass. Some of this you just have to figure out. In many cases it was among the last things you touched as in your case.

Indeed it was! And it was the first place I looked...carefully I thought. Kutos to Dave for pointing out that the solenoid power source comes from the interior blower fan circuit breaker. Who would'a thunk it! I still haven't found it documented anywhere. Certainly a good idea to take the solenoid power off of the ignition switch. Anyway, I looked closer and wiggled the wires on the circuit breaker... wait a second that connector is not actually on the terminal... such a simple thing.

Ron

[DMC-Ron]

Glad you figured it out, Ron.

There is/was a secondary file that went with the original black and white wiring diagram and it was a legend for the wiring colours and components. Do you have that file? I can see if I can find it somewhere.

Figuring the car out can be the easy part. Figuring out all the various quirks and nuances of us folks on the forum here, now that's the tricky part!

Guru's only speak the truth.

Thanks,
Ron