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Discussion Starter · #1 ·
Has anyone ever lost the ground to coils? My C5 started running very poorly yesterday, the codes showed all the left bank coils misfiring. Sure enough I was running on four cylinders(cold exhaust on one side). After checking a few things I found the blk/wht wire on the left side coils was floating(not grounded). I ground it directly to the battery with a jumper and problem solved.


According to the wiring diagrams I have this wire is grounded somewhere on the left side of the engine. Has anyone had this problem / know where this wire is makes ground?
 

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Check the ground wire on another coil....
 

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Discussion Starter · #3 ·
Thanks for the thought. It appears that each bank of coils shares a common ground through the ground wire (blk/wht) that runs in the coil harness. So my left bank ground wire is no longer grounded. At the moment I have the coils grounded with a jumper at the connector for the coil pack; the car runs fine.

I suspect the fix will be to strip the harness back from the connector to where ever it is supposed to be grounded and locate the break. There is a point on the left side of block near the oil filter where wires are grounded to the block, but there must be some intermediate connection for the coil ground as it is not one of the grounds directly connected to the block. So like every other problem I've had with this car(not complaining there haven't been many), the solution is probably behind the intake manifold.
 

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Thanks for the thought. It appears that each bank of coils shares a common ground through the ground wire (blk/wht) that runs in the coil harness. So my left bank ground wire is no longer grounded. At the moment I have the coils grounded with a jumper at the connector for the coil pack; the car runs fine.

I suspect the fix will be to strip the harness back from the connector to where ever it is supposed to be grounded and locate the break. There is a point on the left side of block near the oil filter where wires are grounded to the block, but there must be some intermediate connection for the coil ground as it is not one of the grounds directly connected to the block. So like every other problem I've had with this car(not complaining there haven't been many), the solution is probably behind the intake manifold.
Let us know ... It would make sense to ground the coils back to the battery ground.. I have alway routed my ignition ground and block ground back to the ground point of the battery.
 
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