Okay the F250 i just bought the OD light flashes when the truck is idling... Also the tach is reading 0 at idle as soon as you rev up light stops flashing Which i'll assume is from the tach not working properly. What needs to be changed to correct the tach reading?
DavidD
the OD light is flashing because you have a code, and that code is probably regarding the tachometer. There may be other codes but the E40D will never work right if the FIPL, VSS, or tacho sensor is hosed. The tacho sensor is on the IP gear cover. The leads pull out and it stops working. Sometimes you can shove them back in and glue them into place as a temporary fix. Or it can just get dirty, remove it, clean stuff off it, reinstall. could also be a wiring issue (high impedance due to corrosion) but that's the least likely.
tach
My tach is doing the same thing just toke it off and cleaned it and reinstalled when you crank the engine it will start to read but when it starts it stays on zero and when you hit the go pedal its fine id say its gone into retirement but how can i test it with my dvm what wires do i probe and what is the resistance it should have yes my od light is blinking so i know i have to fix that :ford:thanks
My tach is doing the same thing just toke it off and cleaned it and reinstalled when you crank the engine it will start to read but when it starts it stays on zero and when you hit the go pedal its fine id say its gone into retirement but how can i test it with my dvm what wires do i probe and what is the resistance it should have yes my od light is blinking so i know i have to fix that :ford:thanks
you may be able to score an Electrical and Vacuum Troubleshooting Manual on eBay for around twenty to thirty bucks that will answer all these questions and more, I don't have the documentation handy at this moment unfortunately. ISTR the tach signal wires go to the TECA (transmission electronic control module) and the signal then goes to the cluster. So the wires you want to test are in some awkward location under the dash.
I seem to recall but am not sure that you can also check for power and ground to the tacho sensor from the sensor connector end, one end has either battery or +5 V (forget which) and the other end has ground.
May come back and update. Suggest you get the book whether I do or not.
I seem to recall but am not sure that you can also check for power and ground to the tacho sensor from the sensor connector end, one end has either battery or +5 V (forget which) and the other end has ground.
May come back and update. Suggest you get the book whether I do or not.
OK looked at some 1992 docs, should be identical for these components in 1994 but no promises
engine RPM sensor connects directly to TECA as stated via T/Y and DG wires. TECA mounted to inside of firewall near column and booster.
Remove sensor and check for physical damage to sensor face (resulting from contact with timing gear).
NOTE:
Checking continuity across the terminals of the diesel sensor will show infinite resistance.
Sensor damaged
REPLACE sensor.
Sensor not damaged
Remove sensor and check DC resistance across sensor terminals (with sensor in free air -- no ferrous materials in its immediate vicinity).
l Resistance should be 2000-3000 ohms.
Sensor resistance outside specification
REPLACE sensor.
can't remember where/if I found the instructions on testing what you should see when you probe the wires which go to the RPM sensor
engine RPM sensor connects directly to TECA as stated via T/Y and DG wires. TECA mounted to inside of firewall near column and booster.
Remove sensor and check for physical damage to sensor face (resulting from contact with timing gear).
NOTE:
Checking continuity across the terminals of the diesel sensor will show infinite resistance.
Sensor damaged
REPLACE sensor.
Sensor not damaged
Remove sensor and check DC resistance across sensor terminals (with sensor in free air -- no ferrous materials in its immediate vicinity).
l Resistance should be 2000-3000 ohms.
Sensor resistance outside specification
REPLACE sensor.
can't remember where/if I found the instructions on testing what you should see when you probe the wires which go to the RPM sensor
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
-
?
