no power to fuel pump

**richsues** · 05-05-10 11:58 AM

i have a 2002 sts. the cars died while driving. i checked the fuel pressure and had none. i have no power to the pump. i have power at the fuse and the fuse is good. i removed the relay and have power at one terminal with the ignition off. with the ignition on i have power to a second terminal. i then swapped the relay with one i know is good but still have no power at the fuel pump. i dont know where to go from here? i dont think this could be effecting the fuel pump but the ebcm went out a few weeks ago and i had not got around to fixing it before this fuel problem arose. any ideas where to go next?

**Ranger** · 05-05-10 04:00 PM

Based on your diagnosis there has to be an open somewhere between the fuse box and the pump. You are going to have to start tracing wires from the fuse box to the pump.

I hate to ask, but I have to. You DID check the fuel pressure at key on, didn't you?

**Mark C** · 05-05-10 05:12 PM

Could have a bad ground on the FP relay, don't remember if the ground is at the PCM and it does the switching, or if the PCM switches power to the relay, I'll look it up in the service manual tonight. Jumper the relay out with a short length of wire. find the two terminals that are opposite each other (diagonally across the block), one will have power all the time the other one diagonally across from it will be the feed to the pump, jumper these two. The terminal that has power when the key is on is the power to the coil, the one diagonally across from it is the ground terminal for the coil. If the PCM controlls the ground the ground circuit should open up (resistance goes to infinity) about 2 seconds after the key is turned on.

**submariner409** · 05-05-10 06:03 PM

Down underneath the car, near the bottom front right side of the fuel tank above a protective cover, is the harness connector for the fuel pump module. Get the car up on a chassis lift and pull the connector and clean it - it's a 5 or 6 wire affair.

Yes, I know the 2002 has an access port in the trunk floor: the harness wiring clips won't let you pull enough wire to get the connector up in the trunk...................

**richsues** · 05-05-10 07:03 PM

thanks for the replies. yes i checked the fuel pressure with the ignition on. dont worry im not offended by asking as im new to the forum. i will try the other suggestions and let you know how it goes. thanks again.

**richsues** · 05-05-10 08:36 PM

i tried jumping the the terminals and got the same ohm reading with both the ignition on or off which was approx 40. i ran power to the pump and a seperate ground and the pump ran but didnt cycle off and engine started.

**N*Caddy** · 05-05-10 08:43 PM

With the ignition OFF you should have power between pin C1 and C2 of the F/PUMP relay.
With ignition ON you should have power between the same pins C1 and C2 and in addition you should have power between A1 and C2. Also assuming the relay is inserted and you have a way to check (like looking to the back of the relay socket) then you should also have power between A2 and C2 (C2 is the GND pin).
At the fuel pump you should have power between pin B and pin C (pin C is the GND).
Pin C has a BK wire connected to it and pin B is a GRY wire.
There is an intermediary connector between the fuel pump and the relay. It is a 7-cavity connector located under the right rear of the vehicle, near the wheelhouse. At this connector the pump power is between pin E and G (G is the ground).

**Mark C** · 05-05-10 11:08 PM

Terminals on a 2002 Seville Fuel pump relay are as follows:
C1: Power in from Fuel pump fuse in rear fuse panel Gray or Wht wire
C2: Relay Coil connection to ground at splice pack 301 ground point G301 Blk wire
A1: 12V to relay coil from PCM IGN feed Dk GRN/Wht wire
A2: Power out to Fuel pump Gry wire

G301 is under the rear seat on the driver side just outboad of the fuse panel.

Power to pump from the relay goes thru connector C420 terminal E, Ground for the pump goes thru the same connector in terminal G and grounds at splice pack SP401. SP401 is in the right rear corner of the trunk just forward of the brake lights (my 2000 has a little storage compartment in that corner, its right behind that) C420 is a 7 pin connector E and G are fuel pump power and ground, the rest are power signal and grounds to the fuel sender and fuel tank pressure sensor and is located right at the tank.

If you jumper C1 to A2 (terminals 30 to 87 marked on the bottom of the relay and diagonally across from one another) and the pump runs the circuit to the pump is intact (assuming a good ground at SP401) and you may have an issue on the relay coil side of the circuit such that the relay is not being picked up. This can be caused by either the ground at SP301 being bad, or the PCM is not sending the coil of the relay 12V. The pump will not cycle on and off when you jumper the terminals, as that is controlled by the PCM under normal conditions. (although I'm not sure it does cycle once the engine is running because there are no pressure sensors on the line that the PCM could monitor and use to determine if it should start or stop the pump.) If you don't see 12V at A1 after you tun the key on then you have a PCM issue, or one of the IGN fuses feeding the PCM is blown. Keep in mind the 12V will only be there for about 2 seconds as the FP is normally shutdown after prining the fuel line until the car starts and runs.

**richsues** · 05-06-10 05:53 PM

mark, when i jumpered the c1 and a2 the pump didnt start. i havent checked the grounds you suggested yet but when i turn the ignition i have approx 11 volts at a1 all the time. it doesnt just run power for 2 seconds. with the ignition off i have nothing at terminal a1.

**richsues** · 05-09-10 02:22 PM

i checked all the grounds and all are good. i also checked the connection next to the tank. i have no power at that connection so i have nothing coming out from the fuse box. does that mean its a pcm problem?

**2001_Seville_SLS** · 05-09-10 06:15 PM

I would bet against a bad PCM. There are too many other more likely causes to your problem.

It could be a bad ignition switch or electrical connection. Does the fuel pump work and your car start with the Rear IGN 1 Relay 41 removed? If so check the voltage at IGN 1 Relay 41, circuit 3. It is the contact closest to the driver's seat. There should be 12 volts with the ignition on. If there is less than 12 volts, check circuit 3 at the ignition switch terminal that goes to connector C1 pin B, the one that connects to the pink wire. If you have less than 12 volts at the ignition switch, replace it.

**tccadieldo** · 05-14-10 08:37 PM

Hey Ranger,
This is Tommy you helped me a month or so ago on something. I went on here and thanked you for the help but have not heard from you. Anywho, my problem turned out to be a bad coil pack on my icm. This thread is all about my new problem. The other day my car died at the light and towed it home. I found that my DIS fuse in the eng compartment was blown. I put a new one in and the car ran for 5 min and blew the fuse again. I checked the fuse box and it seems fine so I took the icm to autozone and they tested it and said it was fine. They did mention that it needed dielectric grease on some surfaces and to clean the ground to the icm. I did this and it no longer blew the 20a fuse (DIS). You already know that the dis is for the icm. Hear is the rub, in the process of checking why the DIS fuse blew the same fuse block supports the fuel pump relay and for some reason that relay started to tick violently as soon as I turn the key to the on position. Also, now I got a message (Theft system ...) I think this is cause the battery was run down from tracing the fuse issue, I do not know for sure. I know that when the battery is low it lets lots of gremlins out of cadillacs. I have a diamond white 99 etc. with 115k on it and I love it and plan on keeping it forever. It is the exact car that was the last one made in 02 as far as options, color etc. The fuel pump is 10 month old and I hope I did not fry something although I do doubt it, I was very gentle handling the fuse box but now the relay is going crazy, I tried swapping relays and it ticks also so it is the terminal causing the relay to go nuts. What can cause the relay to do that. Any tricks to check?
Ranger, you are the man, so whatever you recommend I am all over it. I did just have 5 discs fused 5 mo. ago so I need to go about it gently. I am pretty straped for cash also. I did replace the radiator, waterpump, fuel pump, throttle body, motormounts, crank sensors, map sensors, and other stuff so I am a decent shade tree wrench. Electrical is my weak area so be gentle. Thanks buddy, Tommy (tccadieldo)

**tccadieldo** · 05-14-10 08:44 PM

Hey Mark,
This is Tommy (tccadieldo) don't know if its cool to drop in on a string but I can not see the harm. You guys are talking about what I think I am dealing with right now. You guys think this info would apply to my 99 etc? I know it originated from an 02 SLS from richsues.