No power to fuel pump relay

DEREK HARMON

MEMBER
2003 CADILLAC CTS
3.2L
V6
AUTOMATIC
150,000 MILES

Hello, I have the car listed above and the original problem is sputter crank. I looked on YouTube and found a way to jump the starter relay. Did that then the security system kicked in. Now I have no crank at all and no power to the fuel pump. Tested the power to the fuel pump relay and get power constant to one port and turn the key to on but no power to the other port. Please help.

5 Replies

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon,

The load side is fed by the fuse I highlighted in the diagram. That has power all the time.

https://www.2carpros.com/articles/how-to-check-an-electrical-relay-and-wiring-control-circuit

The control side is sent by the ECM for 2 seconds with the key on. It returns when cranking.

Roy

Image (Click to make bigger)

SPONSORED LINKS

Was this

answer

helpful?

Yes

No

Sunday, March 29th, 2020 AT 10:46 AM

DEREK HARMON

MEMBER
3 POSTS

Roger. So with the no crank and no communication with the fuel pump is it safe to say that the eco needs replaced? Switched fuel pump relays to one that I know works and still the same problem.

Was this

answer

helpful?

Yes

No

Sunday, March 29th, 2020 AT 11:16 AM

ASEMASTER6371

MECHANIC
52,797 POSTS

No, not at all.

Did you verify voltage to the relay as I suggested?

You need power to the relay before it can pass power to the pump.

Roy

Was this

answer

helpful?

Yes

No

Sunday, March 29th, 2020 AT 11:21 AM

DEREK HARMON

MEMBER
3 POSTS

There is constant power to the relay. There is no power on the return side when the key gets turned on.

Was this

answer

helpful?

Yes

No

Sunday, March 29th, 2020 AT 5:10 PM

ASEMASTER6371

MECHANIC
52,797 POSTS

The load side has constant voltage. When the control side powers the relay, it closes and sends power to the fuel pump.

The control side power comes from the ECM for only 2 seconds with the key on. It will be constant voltage while cranking.

Did you verify this?

Roy