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sprinkles08
sprinkles08, ASE Certified Technician
Category: Ford
Satisfied Customers: 22694
Experience:  ASE Master and Advanced level certified. Factory trained with 15 years dealership experience
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1991 ford idi 7.3 diesel

Customer Question

1991 ford idi 7.3 diesel
Submitted: 7 months ago.
Category: Ford
Expert:  tims auto repair replied 7 months ago.

Hi, My name is ***** ***** for the delay.
I will do my best to assist you.

Expert:  tims auto repair replied 7 months ago.

please explain your question

thanks

Customer: replied 7 months ago.
No tach have replaced Teca computer, tach sensor , relay
Expert:  tims auto repair replied 7 months ago.

does the engine start and run?

Customer: replied 7 months ago.
No 5v reference signal no od light, yes truck runs great just stuck in third
Customer: replied 7 months ago.
If I jumper around computer I can make tach work
Expert:  tims auto repair replied 7 months ago.

ok,stand by,i will opt out,someone will be right with you

thanks

Expert:  sprinkles08 replied 7 months ago.

Hello and welcome to JustAnswer!

If you have no reference voltage then there is either a wiring issue, the controller isn't awake or it has lost a power or ground feed.

Did you test the reference circuit for a short to ground?

Customer: replied 7 months ago.
Have not yet, will try that in morning , the fact that I have no od light, no tach etc etc but power in leaning towards not proper ground or short, you?
Expert:  sprinkles08 replied 7 months ago.

Either the engine controller isn't awake or there is a wiring issue with the crank sensor.

Customer: replied 7 months ago.
crank sensor??
Expert:  sprinkles08 replied 7 months ago.

Yes, the sensor you said you replaced.

Customer: replied 7 months ago.
Cam sensor
Expert:  sprinkles08 replied 7 months ago.

What was the location of the sensor you replaced?

Customer: replied 7 months ago.
Front of engine 1" wrench . Both new and old sensor specs out correctly when ac multimeter .75 at idle progressive up to 1.8 when revved. If I bypass tranny computer and hook tach sensor to dash via teca plug I get a perfect working tach
Expert:  sprinkles08 replied 7 months ago.

The sensor you're concerned with is on the injector pump gear housing.

Taking a look at the diagram there should not be a 5v reference. Have you tested both wires between the TECA and sensor?

Customer: replied 7 months ago.
Nevermind sprinkles thanks for the help
Expert:  sprinkles08 replied 7 months ago.

You're welcome and good luck with it.