volvo fh 12 truck help needed

[dimitar22]

Hello i need help about 1999 volvo fh 12 truck it has active fault code MID 144 PPID 75 FMI 4

Please if any one can help mo on solving this problem, im trying to solve it for days but no progres.
The issue is that it starts to rise or lover the chasis on the air suspenssion while driving or during stops by it self.

Thank you in advance.

[BRAVO6]

That's a transmission fault, so nothing to do with your problem. Most likely faulty level sensor on the rear axle. There's one on the chassis on each side with a connecting rod onto the axle. The older types are just air valves, later ones are sensors.

[dimitar22]

That's a transmission fault, so nothing to do with your problem. Most likely faulty level sensor on the rear axle. There's one on the chassis on each side with a connecting rod onto the axle. The older types are just air valves, later ones are sensors.

If that is like that why i don't get other fault codes, just this one?
Is it common the inhibitor to do something with this problem?

[BRAVO6]

What year is the truck. Early models only had diagnosis on engine and body controller. No diagnostic for air suspension.

[dimitar22]

it is 1999 electronics 98 i have tested the sensonsr they seeme to be ok.
Can the inhibitor have something to do with this problem?

[BRAVO6]

What's an inhibitor

[dimitar22]

range inxibitor the faut code mid 144 ppid 75 fmi4 is fault about range inxibitor.

[george1]

is there a air pressure sensor usually they have
or be attention to air springs, maybe one is broken
another question: the truck have one or two rear axles ?

[BRAVO6]

No. Definitely wouldn't have anything to do with suspension. Does the suspension go up and down ok when you switch to manual control. If it's ok on manual, it's almost certainly a problem with the sensors. Are the sensors air type or have they electrical connections.

[techbahi]

MID 144 PPID 75 Range inhibitor, solenoid valve status



General information
Display text: Range inhibitor solenoid valve
Component: 614 Solenoid valve, range inhibitor, 3070B Relay, locking 3rd axle
Cable harness: 1000, 1476, 1433A

Error code
FMI 3
Abnormally high voltage or short circuit to higher voltage.

Conditions for error code:

• If the vehicle control unit registers a voltage higher than 6.5 V when the function is active, the control unit interprets this as a fault and an error code is set. Note: The error code is set first at the speed when the inhibitor is to be activated (approx. 40 km/h).

Possible cause:

• Cable between solenoid valve and control unit short-circuited to unloaded voltage (Ubat).
• Faulty solenoid valve.

Reaction from the control unit:

• Error code is set.
• Yellow lamp is requested.

Noticeable external symptom:

• Yellow lamp lights up.
• The range inhibitor is not activated.

Suitable checks:
.
FMI 4
Abnormally low voltage or short circuit to lower voltage.

Conditions for error code:

• If the vehicle control unit registers a voltage lower than 2.3 V when the function is inactive, the control unit interprets this as a fault and an error code is set. Note: The error code is set first at the speed when the inhibitor is to be de-activated (approx. 36 km/h).

Possible cause:

• Break in supply cable forward to solenoid valve.
• Cable between solenoid valve and control unit short-circuited to earth.
• Break in cable between solenoid valve and control unit.
• Faulty solenoid valve.
• Switch resistance and oxidation.

Reaction from the control unit:

• Error code is set.
• Yellow lamp is requested.

Noticeable external symptom:

• Yellow lamp lights up.
• The range inhibitor is not activated or is constantly active.

Suitable checks:
.

[dimitar22]

No. Definitely wouldn't have anything to do with suspension. Does the suspension go up and down ok when you switch to manual control. If it's ok on manual, it's almost certainly a problem with the sensors. Are the sensors air type or have they electrical connections.

It is all ok in manual mode , but while it is standing you can see as it goes up and downo by it self sometimes, sensors have electric harnes on them it has one axle on the rear, but if were the sensors i think there would be other fault codes, there are no other fault codes just this one.

[diagtrucks]

36471-6 MID 144 PPID 75 Range inhibitor status solenoid valve, check
Special tools: 9998533, 9998534, 9998551

Other special equipment: 9510060

NOTE!

• Read off the other error codes for the vehicle control unit.
• Switch off the current in the vehicle using the battery master switch before the connectors are disconnected.
• Check the particular connectors during the fault tracing with regard to loose connection, switch resistance and oxidation. For a detailed description of fault tracing in the cables and the connectors, see separate service information under group 371.

Appropriate tests in the PC tool
The following tests are useful for closely examining the component's function:

• 40005-8 Range inhibitor, test.

Measurement at the component's connector to control unit
Note: Faults in the cable harness to the control unit can damage the component. A check of the component should also therefore be made if any of the measurement values deviate.
Earth cable

1
Prerequisites:

• The connector to the solenoid valve disconnected.
• Adapter connected to the control unit.
• The connector to the relay for the bogie lift inhibitor disconnected (if the vehicle is equipped with air suspension).
• Measuring resistance using the multimeter.
• The control unit connected.
• The ignition key in the off position.
• Measurement to the control unit.

Measuring pointsExpected value2 - earthR ≈ 1.5-2.5 MΩ

Special tools: 9998534
Other special equipment: 9510060

Cable harness
2
For checking the cable harness, see service information under group 371.

Check of component
Note: Faults in the component can be caused by faults in the cable harness of the control unit. A check of the cable harness should also therefore be made before connecting a new component.
Solenoid valve, range inhibitor

1
Prerequisites:

• Measurement box with adapter connected between the control unit's connector PB and the cable harness.
• Ignition key in drive position.
• Check of the solenoid valve.

EarthChecksPB18 - earthListen for sound from the gearbox





Special tools: 9998533 9998551
Other special equipment: 9510060


Check of sub-system
Earth cable

1
Prerequisites:

• Measurement box with adapter connected between the control unit's connector PB and the cable harness.
• Measuring voltage using the multimeter.
• The control unit connected.
• Ignition key in drive position.

Measuring pointsExpected valuePB18 - PB22U ≈ UbatU ≈ 0 V (earth PB18 and listen for sounds from the gearbox)





Special tools: 9998533 9998551
Other special equipment: 9510060


Verification
To check that the fault has been rectified, use the tests in the PC tool (see Appropriate tests in the PC tool).

[BRAVO6]

That fault relates to a lift axle, but there isn't one on the truck, (is there?). You'll need a wiring diagram and check the wires from the control unit that should be going to the inhibitor solinoid. What's history of truck, is it possible there was lift axle before?

Just had a look at a diagram, dont know if it's same year as yours, but range inhibitor solinoid is in the transmission, Check fuse no 9. Should have nothing to do with suspension.

[diagtrucks]

I give you the electric shema

[dimitar22]

I have removed the solenoid valves it thurns out that after the wehicle height goes belov normal it automaticly raises the vehicle if the ignition is on, will replace them with new ones, and will see thank you for your help.