No signal to FP relay
No signal to FP relay 
I am working on a 99 transam. I lost fuel pump when i was driving the other day. I replaced the pump and drove for 5 minutes. Car died with no fuel pressure.
I have12 volts at pin 30 on my FP relay. I do not have any voltage to pin 85 on my relay. I traced the green and white wire back to pin 9 of the red harness at the PCM. There is no power coming out of the pin.
Is there anything that would stop power to and from this pin in the PCM? I do not have a security light on.
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
I am working on a 99 transam. I lost fuel pump when i was driving the other day. I replaced the pump and drove for 5 minutes. Car died with no fuel pressure.
I have12 volts at pin 30 on my FP relay. I do not have any voltage to pin 85 on my relay. I traced the green and white wire back to pin 9 of the red harness at the PCM. There is no power coming out of the pin.
Is there anything that would stop power to and from this pin in the PCM? I do not have a security light on.
The relay will be trigger via the ecu when it sees the crank rotating, and it will ground the relay. There should be no power at this pin whilst the crank is turning there should be ground.
When it is not turning, it may appear as if there is power at it.
Staging Lane
Joined: Jan 2017
Posts: 67
Likes: 1
that is not correct. The PCM sends 12+ to the fuel pump relay, its even stated in the diagram you posted.
The PCM only energizes the relay:
1. During key on to prime the pump for 3 seconds
2. when the crank sensor is reading RPM
if you supply 12+ to pin 85 does the fuel pump run?
Tap into the Drk Grn\white wire 465
(the relay will have to be installed when you do this)
The PCM only energizes the relay:
1. During key on to prime the pump for 3 seconds
2. when the crank sensor is reading RPM
if you supply 12+ to pin 85 does the fuel pump run?
Tap into the Drk Grn\white wire 465
(the relay will have to be installed when you do this)
9 Second Club
Joined: Nov 2003
Posts: 13,616
Likes: 185
From: Norn Iron
that is not correct. The PCM sends 12+ to the fuel pump relay, its even stated in the diagram you posted.
The PCM only energizes the relay:
1. During key on to prime the pump for 3 seconds
2. when the crank sensor is reading RPM
if you supply 12+ to pin 85 does the fuel pump run?
Tap into the Drk Grn\white wire 465
(the relay will have to be installed when you do this)
The PCM only energizes the relay:
1. During key on to prime the pump for 3 seconds
2. when the crank sensor is reading RPM
if you supply 12+ to pin 85 does the fuel pump run?
Tap into the Drk Grn\white wire 465
(the relay will have to be installed when you do this)
