Fuel pump relay issues... (wiring)

[_JohnnyD_]

I'm having troubles getting my fuel pump relay to trip. After doing some testing, I found that pin 85 the ground is not getting a good ground. I've traced the br/wh wire from 85 to pin 1 on X6000 (which is the connector to the DME). Apparently the DME grounds through a few pins (6, 34 and 55). That's where my wiring skill runs out. Could the DME have a poor ground? How do I check? I've tried a second DME with no success.

I've grounded pin 85 with an extra wire and everything works great. The fuel pump relay trips and the engine fires up, idles and revs just fine.

Any advice?

[JGood]

Have you verified continuity from pin 1 of x6000 to the fuel pump relay socket pin 4 (relay pin 85)? A break in that wire is the only reasonable explanation, since the engine runs, so it seems that it is indeed getting ground to the other parts of the harness.

There's only one ground on the engine harness, near the grommet for the factory DME box. You need to make sure this has a good clean connection. Same with the engine ground strap.

I'd also do a continuity test from the x6000 on pins 6, 34, and 55 to the chassis. I skimmed through the ETM, but didn't see a clear indication of which is used for the fuel pump relay ground. 6 is ground for injection valves, 55 is ground for ignition, and 34 is ground for 'remaining output stages'. They all join into the x6452 ground point, which should be that ground near the harness grommet. I think x6000 pin 28 is also a ground that goes through that ground point, but it hits another connecter first, providing ground to the data link connector and the transmission computer (if applicable).

[_JohnnyD_]

Thanks for the advice, I checked continuity from pin 85 on the relay to pin 1 on X6000 and there is a intermittent connection. As I wiggle X6000 I can get a resistance of ~150 ohms and loose continuity. I traced the wire and it looks like it's in good shape so I am assuming pin 1 in X6000 is loose or damaged.

I'm worried about taking the X6000 connector apart, what would everyone think if I just spliced that wire and grounded it? What's the worst that could happen? The fuel pump seems to work fine, it turns on as soon as the key is in accessory mode and turns off ~10 secs after the key is turned off.

[JGood]

Hmm, I'm not sure if that would be an acceptable fix or not. I think that relay sees constant battery power, so that would mean the relay would be energized 100% of the time, even when the car is off. I don't know enough about electronics to know if that's a bad thing. Maybe someone else can chime in.

[mark///m3]

You will need to actually fix it. With the way your doing it the fuel pump relay is staying alive all the time, its strange you actually hear it shut off. Its an intelligent ground which means that it can be switched on or off by the computer and is what controls the relay.