Flashing OD light
09-19-2014, 02:38 AM
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Flashing OD light
1995 F150 Flareside with 5.0 and EOD transmission.
No check engine light is on, but I do read codes 452 and 565. (Insufficient VSS input and Cannister purge circuit, respectively).
So, here's the problem. The OD light starts to flash when the truck intially reaches appox 25mph and keeps flashing until the engine is turned off. When the light is flashing, the cruise does not work, but the Overdrive does. If I stop the vehicle, turn off the engine, then restart and move forward, the same MO starts again. So it's not temperature related. The speedometer works fine.
I have replaced the VSS on the rear axle, but not difference. Checked the DCR of the VSS at the test connector in the engine compartment and get 1.2Kohms.
I checked the wiring schematic which shows the VSS signal going to the speedometer. Then, the output from the speedometer feeds to both the ECM and the cruise control connectors. I was hoping that the problem was in the wiring from the speedo, but I get perfect continuity from the Speedometer output pin, to the ECM and Cruise module. So, either the Speedo output signal is not sufficient or there is a problem with the ECM.
Has anyone had the same symptoms? And, does anyone know the signal voltage vs speed, that is sent from the speedo to the ECM?
Thanks.
No check engine light is on, but I do read codes 452 and 565. (Insufficient VSS input and Cannister purge circuit, respectively).
So, here's the problem. The OD light starts to flash when the truck intially reaches appox 25mph and keeps flashing until the engine is turned off. When the light is flashing, the cruise does not work, but the Overdrive does. If I stop the vehicle, turn off the engine, then restart and move forward, the same MO starts again. So it's not temperature related. The speedometer works fine.
I have replaced the VSS on the rear axle, but not difference. Checked the DCR of the VSS at the test connector in the engine compartment and get 1.2Kohms.
I checked the wiring schematic which shows the VSS signal going to the speedometer. Then, the output from the speedometer feeds to both the ECM and the cruise control connectors. I was hoping that the problem was in the wiring from the speedo, but I get perfect continuity from the Speedometer output pin, to the ECM and Cruise module. So, either the Speedo output signal is not sufficient or there is a problem with the ECM.
Has anyone had the same symptoms? And, does anyone know the signal voltage vs speed, that is sent from the speedo to the ECM?
Thanks.
