i bought a code reader for my 95 f150 with the 5.8 liter engine because it wont start. the code came up as a 542 which is fuel pump secondary circuit fault. what is the secondary circuit. i have replaced the fuel pump resistor and checked the fuses to no avail. any suggestions?
The PCM will ground the coil of the fuel pump relay and then check the output wire from the fuel pump relay to the fuel pump to see if the right voltage is there, if it is not then you will get this code.
You may have a bad fuel pump relay (swap with one of the other relays) or wiring under it.
A bad fuse will do this but you said they were all good.
Some times a bad fuel pump will give this code also and one poster said he had to change the PCM.
But note that the places that remanufacture the PCM say that 80% of the PCMs sent in for repair are good and that there is nothing wrong with them. He may have fixed it by unplugging the PCM and plugging it back in (poor contact).
after working on the problem all day i located the inertia switch located in behind the right kick panel. in my 95 ford the button is red. i popped it up and pushed it back down and the vehicle started. from what i gather in the ford book that resets the fuel pump. i may be wrong about what it does because i do not have the book in hand any more but i do know it works so maybe it will work for someone else
Hi: Sounds similar to my problem sorta, except mine will start if I give it just a squirt of ether or I don't try to start it for a day or so. After it starts I can't shut it off til I'm thru with it because I can't restart it again. I tried to reset the inertia switch but all I did was push down. I'll try to pop it up first then retry resetting it.