420A No spark and fuel pump isnt coming on

[Brian O Conner]

I was trying to fix my speedometer and was trying to see if it was my speed sensor on the tranny or my speedo gauge. I thought if I jumped a power wire from the positive battery post to the speed sensor plug I might get the gauge to move which would rule out the speedo gauge being the problem.

When I did this the car now doesn't get any spark and the fuel pump won't come on now.

All I did is touch the unplugged speed sensor plug with a power wire for maybe a quarter of a second. I checked all fuses which includes engine, gauge, and anti theft. I also swapped the 2 relays on the firewall and it still doesn't get spark or the fuel pump.

Does anyone have any ideas? This was so stupid to everyone out there do not try this. I hope it did not fry the ECU. Thank god there only 179 dollars at Auto Zone.

 

[VelocitàPaola]

Just to be clear, you connected a wire straight from the positive battery terminal to the vehicle speed sensor, which was disconnected from the vehicle's wire harness? If so, I can't think of how that would affect anything that controls the fuel pump or spark. If you connected 12V from the battery to the VSS connector, however, you might have damaged the sensor power supply inside the ECU, which could've taken out the crank and cam sensors.

 

[Brian O Conner]

Just to be clear, you connected a wire straight from the positive battery terminal to the vehicle speed sensor, which was disconnected from the vehicle's wire harness? If so, I can't think of how that would affect anything that controls the fuel pump or spark. If you connected 12V from the battery to the VSS connector, however, you might have damaged the sensor power supply inside the ECU, which could've taken out the crank and cam sensors.

Yes thats what I did. How would I check if its the ECM power supply? Should I check if voltage is going to the Crank shaft positioning sensor? Would that rule out if I fried the ECM? Also what are things to check to determine this? Also is there any fuses that are near the key ignition that are in line fuses that could cause this?

 

[VelocitàPaola]

With the key in the "on" position, you can measure the voltage at the connector. There should be ~8V on the yellow wire (no stripe). Ground is black/green wire. Those correspond to pins 1 and 2, respectively. There's no fuse between these sensors and the ECU, so there's a chance the ECU is damaged if there's no voltage on the yellow wire. This applies to the crank, cam, and vehicle speed sensors.

 

[Brian O Conner]

With the key in the "on" position, you can measure the voltage at the connector. There should be ~8V on the yellow wire (no stripe). Ground is black/green wire. Those correspond to pins 1 and 2, respectively. There's no fuse between these sensors and the ECU, so there's a chance the ECU is damaged if there's no voltage on the yellow wire. This applies to the crank, cam, and vehicle speed sensors.

I am gonna double check that but I also discovered that the fuel pump/ASD relay are not clicking and they are different ones I put on there.

 

[Brian O Conner]

Does anyone know what the voltage/grounds should be on the fuel pump relay? Are there any diagrams out there? I am not getting any grounds but 2 out of the 4 female slots are getting power but the other 2 slots aren't getting any grounds with key on and off?

I can probably diagnose whats going on if I had this information.

 

[Brian O Conner]

Just to specify the voltage I sent with the jumper wire come to find out is ECM 43. Which is the PCM internal ground for CPS, TPS, MAP, Crank Shaft Positioning sensor, and the VSS. The ground wire on VSS is not showing a ground at all with Test light.

Is it safe to say that the ground transistor/Capacitor is destroyed in ECM?

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[steve]

If you connected ECM Pin 43 directly to the battery +12v terminal I would expect some fireworks and then smoke.

 

[Brian O Conner]

All I heard was a pop.

 

[steve]

This is what happens to a 4G63 ECU when you put 12v on the sensor ground. I can't say what happens to a 420A PCM when you do the same since the circuit board is potted but I suspect is not good.

blownsensorground [ECMTuning - wiki]

www.ecmtuning.com

 

[Brian O Conner]

Update i put new ECM car fuel pump does prime and obd2 scanner does work but I am not getting any power to the coil pack whatsoever. Any ideas whats going on? Asd/fuel pump relays are good but only 1 is clicking not the other for some reason.

 

[Brian O Conner]

I ended up changing the Crankshaft positioning sensor and it fixed the car. Car is running. So it fried ECM and Crankshaft positioning sensor. Resolved.