Accelerometer and APS codes

[galexie64]

I have two codes that I have not been able to get rid of.

Efi-444 accelerometer signal

Efi-422 atmospheric pressure sensor signal.

I tried swapping out the accelerometer from my parts car but the code stayed on. I'm not sure it the problem is the sensors or the wiring. I need to figure out how to test the sensors.

I did check voltage to the power wires to both sensors and I have the required 5volts. I also checked ohms to the other wires and they are good.

Is there something I could be missing?
How do I actually test the sensors?

[abscate]

Did you clear codes after replacing parts?

The code format is a bit strange, what reader are you using?

They should read either ECMxxxx or Pxxxx

[scot850]

I can't recall but I think there are 3 sensors on that circuit and those are 2 of them. Any of them could be faulty but the accelerometer is not one that often fails. I have had 2 barometric sensor fails.

You need to reset the fault codes as per abscates. note.

Neil.

[galexie64]

I did reset the codes and they keep coming back. I'm using VOL-FCR 1.7.6

I'll try and get to the junk yard to get a couple of atmospheric pressure sensors to try out.

[galexie64]

I'm still trying to figure out these codes. I pulled an atmospheric pressure sensor out of the junk yard to try out and it didn't fix the problem. I'm not sure if it is a good sensor though. I really need to figure out how to test the sensor to see if it is good. I don't want to spend the money buying a new one and it turns out the problem is the wiring.

Does anyone have the section of the wiring diagram for a '98 turbo car showing these sensors?

[abscate]

We don't host these here by agreement with Volvo legal, but they are public on the web if you google them. You CAN post the relevant parts back here without getting us in trouble, we just have agreed not to archive them here.

[galexie64]

We don't host these here by agreement with Volvo legal, but they are public on the web if you google them. You CAN post the relevant parts back here without getting us in trouble, we just have agreed not to archive them here.

Good to know thanks

[galexie64]

I've still have had no luck getting rid of these codes.

Is there a plug for this harness between the sensors and the ECU that I could pull apart and clean?

[scot850]

Have you checked the ground points? I think the accelerometer has one on the front face of the block low down near the back of the starter motor.

As to the plugs, not sure where/if there is any other than at the items themselves. Still trying to remember what the 3rd item on that circuit was. It may be the high pressure switch on the AC.

Neil.

[RickHaleParker]

You might try disconnecting sensors in the lists below and see if the DCTs change.

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EFI-444 Accelerometer. Signal too high. Permanent fault

Diagnostic trouble code (DTC) information EFI-444

A2300538 Condition
If the engine control module (ECM) senses that the DC signal from the accelerometer has changed its mean setting (2.5 V) to more than 3.5 V or less than 1.5 V, diagnostic trouble code (DTC) EFI-444 is stored.

Substitute value
none.

Possible source
Signal too high:

• short-circuit to supply voltage in signal cable
  open-circuit in signal cable, ground lead or power cable
  short-circuit to ground or supply voltage in power cable
  contact resistance in terminals
  short-circuit to ground in air conditioning (A/C) pressure sensor
  short-circuit to ground in fuel tank pressure sensor power cable
  short-circuit to ground in atmospheric pressure sensor power cable
  defective air conditioning (A/C) pressure sensor
  defective atmospheric pressure sensor
  defective fuel tank pressure sensor.
  defective accelerometer

Signal too low:

• short-circuit to ground in signal cable
  defective accelerometer

Fault symptoms
can store misfire diagnostic trouble codes (DTCs) when travelling on an uneven road.

----------------------------------------------------------------------------------------------

EFI-422 Atmospheric pressure sensor. Signal too high. Permanent fault


Diagnostic trouble code (DTC) information EFI-422

A2301616 Condition
Diagnostic trouble code (DTC) EFI-422 is stored if the engine control module (ECM) receives a signal from the atmospheric pressure sensor corresponding to a height above sea level of over 6.500 m (low signal) or under 780 m (high signal).
Diagnostic trouble code (DTC) EFI-422 is stored if the signal is unstable for 25 seconds (sporadic signal).

Substitute value
the engine control module (ECM) adopts a height of 0 m above sea level.

Possible source
Signal too high

• short-circuit to supply voltage in the signal cable
  open-circuit in signal cable or ground lead
  short-circuit to supply voltage in the power cable
  contact resistance in terminals
  short-circuit to supply voltage in air conditioning (A/C) pressure sensor power cable
  short-circuit to supply voltage in fuel tank pressure sensor power cable
  short-circuit to supply voltage in accelerometer power cable
  defective atmospheric pressure sensor

Signal too low

• short-circuit to ground in signal cable
  short-circuit to ground in power cable
  open-circuit in power cable
  contact resistance in terminals
  short-circuit to ground in air conditioning (A/C) pressure sensor
  short-circuit to ground in fuel tank pressure sensor power cable
  short-circuit to ground in accelerometer power cable
  defective atmospheric pressure sensor
  defective air conditioning (A/C) pressure sensor
  defective fuel tank pressure sensor.
  defective accelerometer.

Signal sporadic:

• loose connections
  contact resistance in terminals
  defective atmospheric pressure sensor
  defective air conditioning (A/C) pressure sensor
  defective fuel tank pressure sensor.
  defective accelerometer.

Fault symptoms
poor performance at high altitude
can cause starting problems at high altitude.