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1992 ford f150 5.0 4x4 auto wont start
6 years 2 weeks ago #20311
by Tyler
Replied by Tyler on topic 1992 ford f150 5.0 4x4 auto wont start
Just to be clear, I see that you've checked for control signal, but do you also have power at the injectors? Just want to make sure that the EEC relay is powering them up as designed. 
If you have a DMM or scope, I'd suggest checking the grey/orange wire at the TFI module during cranking. That's the TFI modules signal to the PCM for injector pulse control. I believe it should be a 0-10V square wave, or about 4-6V on your DMM. Some kind of pulsing needs to be taking place. If you have a good signal, then that'd suggest that the PCM isn't doing its job. If there is no pulsing, then that'd suggest an issue with the TFI or its inputs.
If you have a DMM or scope, I'd suggest checking the grey/orange wire at the TFI module during cranking. That's the TFI modules signal to the PCM for injector pulse control. I believe it should be a 0-10V square wave, or about 4-6V on your DMM. Some kind of pulsing needs to be taking place. If you have a good signal, then that'd suggest that the PCM isn't doing its job. If there is no pulsing, then that'd suggest an issue with the TFI or its inputs.
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