Mamba_153

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An update: Still not starting from start button
Bought a new battery to replace the 6/2017 battery, although it was showing 12.6 volts.
Voltage at Start Button connector (yellow wire) is 13.8 volts, is that indicating something???
Fuel light is still lit and displaying below empty although the fuel tank has 5+ gallons of fuel.


Ignition turns, dings, fuel pump runs, gauges power up
Clutch Pedal Position Switch has connectivity from push start button connector
Starter Relay tested and works
Relay Circuit tested and works
Starter solenoid tested at PDC and engine cranks, engine starts and runs. (I'm bypassing ignition and clutch switch and push button)

I'm puzzled, everything works from the Push Button to the PDC, except it wont turn over. I can bypass at the started solenoid and it will start and run.

Does the ignition switch play a part in the Start Button to the PDC? If so how do I test it? The manual doesn't have a test procedure for the ignition switch.


I'd appreciate help, ideas, I'm jonesing to get out and drive her.

Thanks in advance.
 

MoparMap

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Something about the wiring diagram just doesn't quite make sense to me. It looks like the key gets power from battery and sends that power down through the push button, which then goes through the clutch switch and to the starter relay. That being said, the BCM and PCM also get in on the game and I'm not quite sure how. I think the PCM part makes some sense. It's likely controlling the ground for that connection so that when the engine is running it can open the circuit so the push button doesn't try to start it again. Where it is in the diagram would also support that (it's the only part on the "other" side of the start relay. What I can't figure out is the BCM output for "start" and why it's even there or what it does.
You must be registered for see images attach


It looks like both of them control the starter relay since they splice together at S125, but I don't understand why, unless the BCM is also taking the signal from the switch as an input instead of an output, which I guess maybe makes sense. It might see the "crank" signal and know to shut off stuff like the A/C compressor or blower fan or stuff like that to reduce load on the system.


So the short path seems to be battery -> key -> push button -> clutch switch -> starter relay -> PCM.

If you are getting power at the pushbutton and the clutch switch is working, I guess I would check the terminal at the starter relay to see if it gets voltage when you push the button. If it's getting voltage then the only real thing left in the system I can think of would be the PCM. You might check if the other side of the starter relay coil terminal is closed to ground.
 
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Mamba_153

Mamba_153

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Something about the wiring diagram just doesn't quite make sense to me. It looks like the key gets power from battery and sends that power down through the push button, which then goes through the clutch switch and to the starter relay. That being said, the BCM and PCM also get in on the game and I'm not quite sure how. I think the PCM part makes some sense. It's likely controlling the ground for that connection so that when the engine is running it can open the circuit so the push button doesn't try to start it again. Where it is in the diagram would also support that (it's the only part on the "other" side of the start relay. What I can't figure out is the BCM output for "start" and why it's even there or what it does.
You must be registered for see images attach


It looks like both of them control the starter relay since they splice together at S125, but I don't understand why, unless the BCM is also taking the signal from the switch as an input instead of an output, which I guess maybe makes sense. It might see the "crank" signal and know to shut off stuff like the A/C compressor or blower fan or stuff like that to reduce load on the system.


So the short path seems to be battery -> key -> push button -> clutch switch -> starter relay -> PCM.

If you are getting power at the pushbutton and the clutch switch is working, I guess I would check the terminal at the starter relay to see if it gets voltage when you push the button. If it's getting voltage then the only real thing left in the system I can think of would be the PCM. You might check if the other side of the starter relay coil terminal is closed to ground.
Ok. I give it all a try tonight. Thanks, I'll let you know what happens. I was also thinking running wires and bypass one device at a time.
 
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Mamba_153

Mamba_153

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An update: Still not starting from start button
Bought a new battery to replace the 6/2017 battery, although it was showing 12.6 volts.
Voltage at Start Button connector (yellow wire) is 13.8 volts, is that indicating something???
Fuel light is still lit and displaying below empty although the fuel tank has 5+ gallons of fuel.


Ignition turns, dings, fuel pump runs, gauges power up
Clutch Pedal Position Switch has connectivity from push start button connector
Starter Relay tested and works
Relay Circuit tested and works
Starter solenoid tested at PDC and engine cranks, engine starts and runs. (I'm bypassing ignition and clutch switch and push button)

I'm puzzled, everything works from the Push Button to the PDC, except it wont turn over. I can bypass at the started solenoid and it will start and run.

Does the ignition switch play a part in the Start Button to the PDC? If so how do I test it? The manual doesn't have a test procedure for the ignition switch.


I'd appreciate help, ideas, I'm jonesing to get out and drive her.

Thanks in advance.
OK FIXED sorry it took so long to update. It was a short with the fuel gauge. Simple fix.
 
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Mamba_153

Mamba_153

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OK FIXED sorry it took so long to update. It was a short with the fuel gauge. Simple fix.
Good lessons learned. Be patient, read your manuals carefully, trace continuity and voltage wire by wire and connector by connector, and be methodical. You'll find the electrical problem. These Vipers are super well designed and easy to fix, if you don't rush.
 

MoparMap

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Good lessons learned. Be patient, read your manuals carefully, trace continuity and voltage wire by wire and connector by connector, and be methodical. You'll find the electrical problem. These Vipers are super well designed and easy to fix, if you don't rush.

Glad you got it fixed! That's a pretty weird one though, but I guess that's kind of how electronics are anymore. Stuff you wouldn't think is related at all can cause some funky issues. The fog light switch in my turn signal stalk was acting up once and allowing the fog lights to come on without the headlights like they normally do. The strange part is when they did come on the A/C compressor indicator on the temperature control cluster would as well. No idea how they were related, but just goes to show an issue in one place can result in symptoms somewhere else entirely.
 
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