From previous thread.
Vauxhall Astra G fuel injection pump control unit was to the best of my ability diagnosed as malfunctioning, I concluded that using TIS checking procedure that the control units pins 1 and 2 did not have a voltage present, recording 00.04v
I sent the fuel injection control unit to be tested and repaired if required, I received a telephone call Friday afternoon to advise that the control unit was faulty and that a repair had been carried out.
After refitting to the fuel injection pump, I decided to carryout the TIS checking procedure again to establish what the differences are, I could possibly have misunderstood some of the check procedures, or they could be badly worded, advise what you think?
I started with a code, the only code P1631 fuel injection pump malfunction 3. Communication error between injection pump control unit and engine control unit.
T011 asked to check for a short to ground, interruption of voltage supply, this is the main battery feed from the ignition control relay when the ignition is switched on.
T011 asks the technician to disconnect the injection pump harness connector and check for a voltage supply, advising that a nominal voltage greater than 11V should be recorded, however this checking procedure may look ok but is not load tested?
The battery at this time was not fully charged and I chose to leave the connector connected into the fuel injection control unit while testing the voltage, I recorded 11.97V
T012 asks to check circuit interruption of ground circuit.
The work order description does not advise whether the fuel injection control unit connector should be connected or disconnected during this checking procedure. I chose to leave the connector plug connected to the control unit and recorded a voltage of 11.92V
T013 asks to check for a short to ground interruption of voltage supply circuit.
The check asks for the voltage to be measured between the injection pump control unit terminals 6 and 5
I already understand that terminal 6 is a ground reference so that terminal 5 must be the voltage supply, but where from?
Is the voltage supply from the fuel injection control unit or the ECM?
The work order description does not make it clear if the fuel injection control unit connector should be connected or disconnected?
The nominal value is advised to be greater than 11V. With the connector plug connected the voltage was 00.08V, and disconnected it was 11.08V
Its clear now that terminal 5 is supplied a voltage reference from the ECM terminal 105. This test has been carried out after the fuel control unit has been repaired, so there is no doubt that the TIS instruction should of advised that the fuel control unit connector should have been disconnected for this check procedure, which it does not.
T020 asks for the ignition to be turned off and the ECM to be disconnected. Then the procedure asks for the resistance between terminal 105 of the harness connector and ground to be checked, advising that a resistance greater than 500 kOhm should be recorded, the result did record greater than 570 kOhm
T014 asked for check to be carried out to confirm or dismiss a short to voltage of signal circuit, the nominal value being 0.3V, the actual reading was 0.04V
T016 asked to check component fuel injection control unit pump for a voltage between 0.5...4V. I measured this voltage before the fuel injection control unit was sent away and recorded 00.04V, at this point I took it that the control unit was faulty, however after fitting the fuel control unit back on after repair I got the same reading as before, so although TIS does not advise to disconnect the connector from the fuel control unit, I decided to check the voltage with the connector disconnected, I found that the voltage now read 1.60V
T018 asked for check short to ground/interruption of signal circuit.
With the ignition off and the connector to the ECM disconnected the check procedure asked to check the resistance between terminals 99, 100 & ground.
The nominal value should be greater than 500 kOhm, the actual value was 1065 Ohm in each case. On the fuel control unit prior to sending away for repair I recorded the exact same readings here as I did after the control unit had been repaired.
I tested the wiring between ECM terminal 99 and Fuel control unit terminal 1 and found no fault, I also did test the wiring between ECM terminal 100 and fuel control pump terminal 2, I found no fault.
TIS advised at this point that the fault is within the fuel injection control unit.
Yes its a lot to take in, but the readings on terminals 1 and 2 were no different when the control unit was returned to me, and the resistance checks for terminals 99, 100 and ground came back at 1065 Ohm, which is exactly the same readings before the control unit was sent away and returned.
The fuel control unit was refitted and fault code cleared, the engine started and runs OK, a long road test and no codes have come back. It seems that technical detail has changed and TIS was not updated, had I of checked the voltage at pins 1 and 2 with the control unit connector disconnected prior to sending the unit away and got the same results as now, I would say I have no idea how the checking procedure of TIS could actually lead to a conclusive diagnosis.
To conclude I am not really sure If I have learned much from this experience except maybe technical information can be misleading. I learned after the experience from another garage that there is a tool that connects the fuel injection control unit to the ECM and checks the circuits out to establish electrical faults, if I would have known this I would have borrowed the tool to make the job easier.