Electrical Code 22 - New BAP and resistances all good


New Member
Nov 13, 2022
I have been troubleshooting a Code 22. I have an 87 but the car has an 89 Harness and A9L ECM, full MAF conversion.

-I checked the test harness ground and its good.
-I checked the resistance between the MAP/BAP connector, TPS connector, and EGR connectors (ground wires) and all checks good.
-Resistance from the BAP/MAP sensor plug to ground (neg battery terminal) is good.
-The BAP/MAP connector shows 5V with the ignition on, orange wire.
-All pointed to a bad sensor. My DVM doesn't read HZ so I took the chance.

-I swapped the MAP sensor for a new NAPA BAP sensor and no change to the codes.
-I had a bad experience with a bad/new EGR sensor and so I bought a second new BAP sensor "Standard" brand from O'reillys and no change to the codes.

-The A9L ECM was recently refurbished due to a couple burned pins caused by a burnt O2 sensor wire.

I am at a loss on what to check next. Maybe the ECM isn't getting the signal, a break in the wire somewhere?

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I would test to see if the ECM is receiving the signal back at the ECU.

You really need a meter that measures in HZ to test MAF function, but a voltage is output so you can use that voltage to verify that the signal from the MAP/BAP is making it down to the ECU.

DOwn at the ECU, the pin for the MAP/BAP is pin 45. You can probe at the ECU between that and pin 46 (sensor ground) to see if the signal is making it.

Also, just to verify, since oyu are using an 89 harness and A9L, the vac line to the MAP is removed correct? Port is open as now the sensor is being used as a BAP (Barometric Pressure)

Also, when checking for codes, it's a good idea to erase all the codes, restart the engine a few times, and then pull the codes. Sometimes old codes can linger.
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Here is the latest.

I have re-verified the resistances. Interesting side note, the resistances are all in spec with the ignition off but the doors need to be shut and underwood light disconnected. Otherwise those lights mess up the resistance readings....usually around 7.5 ohms. Otherwise, with the negative battery terminal disconnected all resistances are down around .3 ohms to the terminal connector.

I have also used my DVM to verify connective down to the ECM connector. Pin 45, 46, 25 and other associated pins are all good. I cleaned all the related grounds including the main negative batter terminal ground. The car runs smoother but I am still getting code 22. Additionally, I verified the ECM internal ground between pins 40 and 60 is within spec.

I also ran an additional ground from the test connector. That lowered the resistance a little more but it was already in spec. I wanted to rule out a bad ground as the problem as everything else checked good.

I am leaning towards both the Standard BAP and the NAPA Bap both putting out bad signals. I can't verify this but what else could it be. I think I may need to purchase a Ford Motorcraft BAP. Otherwise I think I have ruled out any other possibility.


I see you've whittled the issues down to one...Great Job getting that far and Im glad to hear the car is running alot better.

As far as the MAP sensor being out of range setting......You stated that the wiring was upgraded to 89 w/ MAF and an A9L....?

Any chance you have a vacuum line hooked up to the MAP/BAP nipple?...If so...;-

When utililizing a MAF sensor the MAP sensor loses its vacuum line to become a BAP with an open nipple and the only reason I could think why your problem exists other than your thoughts on what it is......

MAP = Manifold Air Pressure..Should of been called MVS = Manifold Vacuum Sensor

BAP = Barometric Air Pressure and reads where the vehicle is in relation to SeaLevel.
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I do not have the vacuum line hooked up.

I also recently purchased a new Motorcraft BAP/MAP. Still getting code 22. I am letting the car sit with the negative battery terminal disconnected just in case its not properly dumping the codes through the reader.

I re-verified, for the third time, that all resistances are good. I am beginning to think it could be a connector problem... maybe a bad connection inside the connector. I have a spare I can try but I dont want to hack my harness if I can avoid it.