In the age of diagnostics, communication between the vehicle and your scan tool is critical. When this doesn’t happen, it can be a frustrating search for the cause of that before you can get down to fixing the vehicle’s problems. SureTrack community member BekarAuto had a Ford Super Duty pickup in the shop that wouldn’t start and the scan tool couldn’t communicate with the computer. They posed the question to the community, and with the help of fellow community member jhirz and others, they were able to resolve the issue quickly.
The following Community Fix summarizes the interaction between members of the community that led to the solution.
1999 Ford Pickup F250 Super Duty 7.3L
No start, no communication, replaced exhaust back pressure sensor.
Customer complains that truck won’t start.
Diagnostic Steps Performed/Parts Replaced
Truck came in as a no start. Checked all the typical no start electrical items. Tried to scan for codes but found no communication issue with the computer. Have power at DLC. No blown fuses and all relays check out as good. Any suggestions before I start ripping into wiring harness looking for shorted wiring?
Best Answer from Community Member jhirz
Try unplugging the exhaust back pressure sensor on front of engine. It’s a three-wire sensor, wire colors of BR/W, P/LG, GY/R.
Exhaust back pressure sensor was bad, unplugged and truck started.
Replaced exhaust back pressure sensor, truck starts normally and scan tool can communicate with computer.
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