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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,274
"Paul, your car is driving me bannanas! Mystery wiring jobs...uuggghhh!

So, she runs without the OB sensor wire attached. That's interesting, someone bypassed/rewired the protection circuit. Without that wire connected to the OB sensor, then how can the sensor sense overboost conditions and shut her down at 1.2 (or any) bar? The sensor is a normally closed switch that connects the wire to ground...which keeps the pumps running. Overboost opens the switch and interrupts the ground and shuts down the pumps."

This can be done by simply grounding the white wire from the overboost sensor next to the speed relay under the driver seat.
Maybe someone got sick of the overboost circut or didn't want to buy a new sensor and did that in the past.

The yellow relay is not the overboost relay like everyone thinks, the "speed relay" under the driver seat has two internal relays on it's board and handles more than one function.
This "speed relay" farthest to the left under the driver seat disconnects the 2 red fuel pump relay grounds when the overboost sensor disconnects the white wire from ground. It also disconnects the red fuel pump relay grounds if rpms go somewhere around 7000-7200 rpm so it is also the factory rev limiter.
Old 07-28-2010, 12:41 PM
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