Cam and crank bad grnd

[DanielDSM]

95 eclipse 4g63 I couldn't get car to start no fuel or spark so checked my cam and crank sensors I have 12v on Red wire 5v on blue and continuity to ground on both connectors when switch is off, but when i turn ignition on I lose ground I also lose ground on tps and ignition coils plug which are in line with the cam and crank wires does the ecm switch the ground off or do I have a bad ecm

 

[DanielDSM]

Is there a way to find out if the computer is suppose to switch the grounds on these sensors?

 

[motomattx]

The computer doesnt switch anything, the sensor switches them and the ecu looks for those switches, that is how they function.

 

[DanielDSM]

Ok then what would cause me to lose my ground when switch is turned on cause I'm losing it at the cam crank sensor and coils and tps that's all I checked I can go further but they all run in same harness

 

[DanielDSM]

How would I go about finding out what's causing me to lose ground when my ignition is turned on it's fine with ignition off

 

[motomattx]

Have you checked all fuses in both fuse box's? and have you cleaned all grounds including the ground from the body to the engine? what lead up to this?

 

[DanielDSM]

Well I bought the car with a blown motor so took it out and rebuilt motor and head all new timing parts new cam sensor crank sensor all grounds that I know of have been cleaned and re installed my head and block our grounded I have checked all fuses and they are good motor will turn over but I get no spark or fuel so checked cam and crank sensor they have 12v on red wire 5v on blue and ground continuity is good until I turn the ignition key on then i lose ground to both cam and crank coils tps those are all i have checked cause they are in the same area as cam sensor so i was wondering if the computer is causing the issue with losing ground or maybe the ignition switch itself

 

[DanielDSM]

I know when I took the old can sensor of it was melted but dont know if that could cause something to short out, when I bought the car the guy said he had it running and it just quit found out it had bad compression, so I have never had the car running but I do know that the ECM isn't showing any codes

 

[motomattx]

It sounds like something is shorted, you should have 5v on one terminal, ground on another terminal and pulse on the third terminal. Maybe try running a ground from the chassis to the ground terminal on the sensor.

 

[dustyboner]

https://www.ecmtuning.com/wiki/blownsensorground

 

[DanielDSM]

Thx guys I'll try what u said, I'll check the sensor ground in ecu thx dusty

 

[DanielDSM]

Well I took computer apart and the pin 92 looks good

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[dustyboner]

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[DanielDSM]

So check the ground to the ignition switch

 

[DanielDSM]

Ok so I replaced the battery for car cause it wasnt holding a charge I now have a good ground with key on but I still dont have spark or fuel injectors arnt firing with the diode light in the harness would think i need to replace crank sensor

 

[motomattx]

Have you tried swapping a new ignition transistor?

 

[DanielDSM]

Yes I replaced that and put new coils in