P38A Lack of earth.

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tomcat59alan

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wirral and triquivijate
Afternoon, been playing with electrickery this morning ( dangerous I know). My newish fuel pump stopped working and it seems the earth is not being granted to pin 1(86) on relay 12. Is this granted from the becm directly or indirectly through the inertia switch. Where are the Wizards today?:eek::D
 
Pin 1 on RL12 comes from a feed off RL19 according to my RAVE. Check F39.
Peter

RangieFuelRelay1.jpg
 
Dont know if it matters but this one (the black one) is a 96, was a 4.0 but now a 4.6. I have power to pin 3 and switched power to pin2 .If I link pins 3 and 5 the pump runs its just the lack of earth at pin 1 that is stopping the rely from pulling in. Regards Alan
 
The FEED from RL19 would not be a ground, it would be 12v+, Pin 2 needs to be grounded to operate the relay, assuming Pin one is fed with 12V.

The ECM controls the relay via Pin 18 C0635 connector.

Peter

RangieFuelRelay2.jpg
 
This is why I hate electrickery.. I have on relay 19, pin 5 neg, pin 2 pos, pin 3 pos and pin 1 switched neg when ignition on. On relay 12, pin 5 neg, pin 3 pos pin1 neg for 2 seconds when ignition switched on and pin 2 neg when ignition :confused: on. :mad: Relay19 sounds ok to me with the relay cutting in only when the ignition is on but relay 12 would only operate the fuel pump for 2 seconds or perhaps that's right. I await with baited breath.
 
if I remember correctly the engine needs to be cranking for the fuel pump to run
 
Moron said:
if I remember correctly the engine needs to be cranking for the fuel pump to run
Click to expand...

The fuel pump runs for 5 seconds and then shuts off until the engine is running, signalled by the crankshaft sensor sending pulses to the engine ECU.

The fuel pump is shut off if the Inertia Switch is activated also.

Peter
 
Not sure if this information will help but when my alternator was acting up the fuel pump ran continuously when I switched off, even though the car was locked etc. In the end I had to pull fuse 39. You appear to have the opposite problem. So maybe whatever caused mine to be switched on permanently is switching yours off permanently? A relay being permanently shut, maybe?
 
GEMS%20fuel.jpg


That's the RAVE picture from the 1996 ETM for the fuel pump.

Fuel pump relay has a '15' (Ignition switched, pos II/III) feed to the coil of the relay (pin 1). The other side is then connected to the engine ECU to ground it and power the fuel pump, when the engine ECU calls for it (relay pin 2).
The relay contacts have 12V permanent on Pin 3 from F39, and then the Pin 5 feed to the fuel pump goes to the bit that says A1-6 'B'

This is one side of the inertia switch, which is a normally closed contact, that feeds the fuel pump. If this is tripped,, then it disconnects the +ve feed from the fuse box/relay to the fuel pump, and grounds an input to the BECM to tell it that it's been tripped (also I think brings up a dash warning, and will unlock all the doors, put the hazards on etc if it is actually tripped.

You will see a connection to ground (through the pump motor winding) on pin 5 with the relay removed. You should see permanent 12 on Pin 3. You should then see 12v on pin 1 when the ignition is in position II/III, and then the pin2 should trigger to ground for a few seconds when the ignition is in position II and then disappear. it would then normally activate once the engine is running to keep the fuel rail pressurised.
 
martyuk said:
GEMS%20fuel.jpg


That's the RAVE picture from the 1996 ETM for the fuel pump.

Fuel pump relay has a '15' (Ignition switched, pos II/III) feed to the coil of the relay (pin 1). The other side is then connected to the engine ECU to ground it and power the fuel pump, when the engine ECU calls for it (relay pin 2).
The relay contacts have 12V permanent on Pin 3 from F39, and then the Pin 5 feed to the fuel pump goes to the bit that says A1-6 'B'

This is one side of the inertia switch, which is a normally closed contact, that feeds the fuel pump. If this is tripped,, then it disconnects the +ve feed from the fuse box/relay to the fuel pump, and grounds an input to the BECM to tell it that it's been tripped (also I think brings up a dash warning, and will unlock all the doors, put the hazards on etc if it is actually tripped.

You will see a connection to ground (through the pump motor winding) on pin 5 with the relay removed. You should see permanent 12 on Pin 3. You should then see 12v on pin 1 when the ignition is in position II/III, and then the pin2 should trigger to ground for a few seconds when the ignition is in position II and then disappear. it would then normally activate once the engine is running to keep the fuel rail pressurised.
Click to expand...
Thanks for your patience people, on the fuel pump relay(12) I have permanent +'ve on pin 3, permanent -'ve on pin 5, switched +ve on pin 2 and switched -'ve on pin 1 for a couple of seconds.So pins 1 and 2 are opposite to what you say Marty but should that matter?
 
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