Ok thanks.
I cant seem to find the fusible link. There is a cartage type fuse immediately after the Positive terminal at the battery which the diagram doesn’t show, but it does show an inline fuse / fusible link on the negative side, that I cant seem to find.
Do you mean “at the start solenoid” as labeled in your diagram?
No I was referring to the S cavity for the relay in the engine compartment fuse box. Im getting no reading at the S (control) post/wire on the starter.
What does the S cavity connect to?
I assume that it is connected to the control side of the starter(?)
So, you’re measuring 10.5 volts in the S cavity of the starter relay with the relay removed?
Yes that is correct
Disconnect the small wire at the starter solenoid and see if you still get that 10.5V.
Just re-read this…do you see how you are saying there is 10.5V at one end of a wire (purple/red) but 0V at the other? Also, with the relay out, I can’t see any source for the 10.5V there.
Seems to be the wrong relay cavity or the wrong relay location. The cavities usually are not marked with a “B” or “S” and that is not shown in the diagram, the use of “B” and “S” makes it difficult to understand which circuit and location you are testing.
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Yes I see what you are saying, but I cant say for sure that there isn’t an inline fuse on that wire or that the wire/connection is damaged somehow.
The cavities that the relay sits in are not marked, its possible that I am misidentifying them. I was under the impression that the B was designated as constant power and the S was the control.
Here is how it looks, with key “run” position:
10.78V while probing the top left cavity (87), with key in Run position. Similar reading from bottom left cavity (86), when key is turned to Start. I think the reduced Voltage readings are simply surface readings reduced because of fuel pump etc operation when relay had been removed for a few minutes. (EDIT)
(Sigh) So what happened to 12.45V on “B” reported before??
It sounds like you are on the track to find the problem. Voltage testing done by disconnecting parts of the circuit is a good idea for getting an idea where the problem is, but that method can lead you to thinking something is working when it isn’t. To do a proper diagnostic voltage test everything must be connected, and all the pertinent relays installed. Sometimes I’ll hook up test wiring leads to allow me to probe certain points in the circuit with everything connected. I’ve soldered test leads to pins on relays for example. Suggest to re-connect everything, and measure & report the following 6 voltages with the key in “s” and gear selector in park.
- Battery + to battery -
- At the top of the fusinble link to battery -
- At the bottom of the fusible link to battery -
- At the top of the purple wire to battery -
- At the start terminal on the starter motor to starter motor case
- At the start terminal of the starter motor to battery -
You testing reported above, if I understand correctly, suggests there is a bad connection between the starter relay and the s terminal on the starter. Or the starter solenoid coil is shorted out. Be aware this might cause something to heat up as you do the testing above, and melt wire insulation or something. So only turn the key to “start” briefly, just long enough to do one voltage measurement.
At least you know now why it won’t crank. Zero volts on the “s” terminal of the starter.
I’m sympathetic to your volt meter problems. Mine went south on me the other day and got me confused during a voltage measurement. Turned out the wire inside one of the probes had come unsoldered.
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Turn the relay over. Do you see the numbers 30, 85, 86, and 87 anywhere? If so, add where those pins would go on your picture of the relay socket.
On your diagram, for the starter relay as shown, it would normally be:
Lower-left connection…30 (to S on starter solenoid)
Lower-right connection…85 (ground)
Upper right connection…86 (start signal)
Upper-left connection…87 (battery positive)
Edit: But, 85 and 86 can be reversed, and 30 and 87 can be reversed as shown by @Nevada_545 below.
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Assuming that @insightful is correct, then you should see about 12.45 volts on terminal 86 of the socket when the key is in the start position. There shouldn’t be anything there in any other position. Terminal 87 should be hot all the time.
If you have that, then put the relay in and check for 12V on the small terminal of the starter solenoid. It should only have voltage with the key in the start position. If it does, the starter should crank. If it doesn’t, then something is wrong with the starter.
Many starters use a blade (spade) terminal for the ignition terminal on the starter. The ignition wire to the starter uses an insulated female blade. If this is the case and you have to unplug the ignition wire to check for voltage and you do find voltage, it is possible that the insulated connector is defective. What can happen is the conductor is no longer seated in the insulator and when you put it on, it backs up into the connector and never makes good contact with the blade on the solenoid. Just something to check.
The wires to the terminal could be frayed and broken at the terminal as well.
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Pins 85 and 86 are for the relay control.
Pins 30 and 87 are input and output.
Pins 85 and 86 are positioned diagonally from each other, same with 30 and 87. This allows the relay to be installed either way with the same results.
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OP’s test lead in the photo seems to be connected to a rivet to the left of the relay. Is there a reason for that ? Or am I seeing where the test lead is connected incorrectly?
You should have continuous power on one of the cavities, the fusible link must be blown.
Your guys’ patience is appreciated. I’m learning the starting system and how to test it as I go.
- Battery+ to battery- 12.40v
- At the top of the fusible link to battery - 12.40v
- At the bottom of the fusible link to battery - 12.40v
- At the top of the purple wire to battery - (Wondering how to test this, are you referring to the slot 86 ‘start signal’ cavity?)
- At the start terminal on the starter motor to starter motor case - 12.40v (assuming start-signal wire)
- At the start terminal of the starter motor to battery - 12.40v
I agree with the idea of the possible bad connection between the starter relay and the S terminal on the starter, can’t seem to find it though. I think I can rule out the starter solenoid coil shorting out because Ive switched the starter/solenoid out with another unit and nothing changed.
The only thing I can find resembling a fusible link is attached to the positive battery terminal; it is actually a cartridge type fuse (picture included). This is where I took top/bottom readings from. Is this the one noted in the diagram or is there one somewhere else?
What might indicate the ignition switch has shorted out? The fuel pump and accessories activate when key is turned to Run, but as mentioned, no crank when turned to Start.
