If you're seeing dropout on other sensors then that's a good indication you have a problem with the 5V reference voltage used for the sensors. It could be the PCM
but you have to rule out the wiring first.
Check for 12V on PCM
pins 55, 71, and 97. Check for good grounds (0 volts) on pins 25, 24, 51, 76, 77, 103, and 33. You have a Windstar so I'm not sure of the ground locations, but there is usually one near the PCM
. I suggest cleaning it.
Today I did the testing.
Pins 55. 71, 97 all have 12v
24, 25, 51, 76, 77, & 103 have 0.036V, forgot to do #33.
sensor Gound 1.09V, and ground return 1.09V.
Does this mean that the sensor has a short and return voltage is going thru the sensor? Would cutting the ground for the MAF
and hooking it up directly to the battery negative do any good?
I did get a 4 gauge battery cable and attached it to the negative battery post and a long threaded stud on the Upper intake manifold.
I have not gotten a new sensor, wanted to wait for testing of PCM
Thanks for advice.
Yesterday when I had the laptop hooked up again I stopped at a store and disconnected the software by hitting the disconnect button. When I returned and pushed the connect button the
software would not communicate with the PCM
. I tried several times. Finally I completely disconnected the tool and hooked up my cheap code reader to see if it would communicate and it worked. I then reconnected the laptop and it did communicate with the PCM
. This did happen once before since dealing with the used no functional MAF
sensors. I have not tried the laptop with any other vehicles since this has occured so I am not sure if it is the software or the PCM