Faulty Signal
SPECIAL TOOLS
Test box tool No. 981 3190, or equivalent
Volvo scan tool No. 998 8686, or equivalent
FAULTY SIGNAL
1. Checking Load Signal
- Preparation:
Start engine.
Select scrolling values
Read load signal.
- Normal range idling with warm engine, N position and A/C off: approx. 35 micro seconds This value increases with load.
YES: Proceed to step 12
NO: Proceed to step 2
2. Connecting the test box. Checking ground terminals
- Preparation:
Ignition OFF.
Connect the test box and check ground terminals. Connecting the Test Box
- Then continue with step 3
3. Checking signal cable for short-circuit to supply voltage
- Preparation:
Ignition OFF
Transmission control module (TCM) connected.
Ignition ON.
- Connect an test light (bulb at least 3 watt) between #42 (B#12) and #20 (A#20) on the test box.
- The test light should not light.
- If reading is OK:
Proceed to step 5
- If reading is incorrect:
Proceed to step 4
4. Checking for a short-circuit
- Check cable between TCM #B12 and Engine Control Module (ECM) #B12 (Fenix 5.2, LH 3.2, EZ 129K, Motronic 4.3 or Motronic 4.4) for a short-circuit to supply voltage according to step 4 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 10
5. Checking signal cable resistance to ground
- Preparation:
Ignition OFF
ECM disconnected. (On cars with LH 3.2/EZ 129K both control modules LH 3.2 and EZ 129K.)
Transmission control module (TCM) connected.
- Connect an ohmmeter between #42 (#B12) and #20 (#A20) on the test box.
- Does the ohmmeter read infinite resistance?
- Yes:
YES: Proceed to step 7
NO: Proceed to step 6
6. Checking for a short-circuit
- Check cable between TCM #B12 and ECM #B12 (Fenix 5.2, LH 3.2, EZ 129K, Motronic 4.3 and Motronic 4.4) for a short-circuit to ground according to step 3 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 10
7. Checking signal cable
- Preparation:
Ignition OFF.
Connect the TCM
Connect ECM. (On cars with LH 3.2/EZ129K both control modules LH 3.2 and EZ 1 29K)
Start engine.
Select SCROLLING VALUES
Read load signal. Normal value at idling speed with engine warm, N position and A/C off is approx. 35 micro seconds. This value increases with load.
- Does value increase with engine load?
- Yes:
YES: Proceed to step 8
NO: Proceed to step 9
8. Checking for a short-circuit
- The Diagnostic Trouble Code (DTC) was caused by poor contact in the TCM connector.
- Remedy short-circuit to ground in TCM according to step 5 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 10
9. Checking for an open-circuit
- Check cable between TCM #B12 and ECM #B12 (Fenix 5.2, LH 3.2, EZ 129K, Motronic 4.3 and Motronic 4.4) for an open-circuit according to step 2 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 10
10. Verification
NOTE: After repairs have been completed they must be verified as follows to ensure that the fault has been eliminated:
- Preparation:
Ignition OFF.
Reconnect the connectors, reinstall components etc.
Ignition ON.
Go into scrolling values.
Read load signal.
Engine idling.
- Normal range idling with warm engine, N position and A/C OFF: approx. 35 micro seconds. The value increases with engine load.
- Yes:
Fault corrected
- No:
Proceed to step 11
11. Fault-tracing information
- The verification result shows that the fault persists.
- Do you want to exit fault-tracing?
- Yes:
Fault not corrected
- No:
Proceed to step 1
12. Intermittent fault
- Check transmission and engine control module connectors for contact resistance and oxidation according to step 6 of checking for intermittent faults. Checking For Intermittent Faults
- Check cable between TCM #B12 and ECM #B12 (Fenix 5.2, LH 3.2, EZ 129K, Motronic 4.3 and Motronic 4.4) for:
An intermittent open-circuit according to step 2 of checking for permanent faults. Checking For Permanent Faults
A short-circuit to ground according to step 3 of checking for permanent faults. Checking For Permanent Faults
An intermittent short-circuit to supply voltage according to step 4 of checking for permanent faults. Checking For Permanent Faults
- Then continue with step 13
13. Fault-tracing information
- For intermittent faults fault-tracing is not followed by a verification because the fault is not present at this moment.
- Do you want to repeat fault-tracing?
- Yes:
Proceed to step 1
- No:
Operation done