Switched 12v question

[smee123]

Gents, I noticed that my switched 12v to the fuse box in the engine bay, and subsequently to the dme via the blue relay, stays on after the key is out. Has anyone experienced this before? If so, what was the resolution. Car in question is a 2004 330 zhp, in the process of being s54 swapped. Could the extra s54 stuff be making a relay stick inside the car?

[heinzboehmer]

IIRC, the DME is powered directly off a fuse when key is turned, not through a relay. The relay I think you're referring to is for the engine electronics (sensors, solenoids, etc.) and is controlled by the DME. So I would be looking at the DME or the relay itself.


Edit: Dug up some wiring diagrams.

DME supply (X60001):



I think pins 1, 7 and 8 are all on the same power plane inside the DME, but it's been a while. This would mean that K6327 (fuel injector voltage supply relay) gets switched on whenever the DME receives power. Can check later on my spare DME if it's helpful, but that's not really your issue here.


Relevant part of DME signals (X60002):



I think K6300 is the relay you're referring to. Here's the wiring diagram for that:



Does the fuse box lose power when you disconnect X60002 from the DME? If so, then the DME is driving that signal pin for some reason. Otherwise relay is to blame.

[smee123]

Haven't tried that yet. I noticed today that the pcv solenoid was burning hot. I had power at the single red wire coming from inside the car which drives the blue relay inside the engine bay. There are 3 switched 12v coming into the fuse box upfront. The single plug one is the one that stays on for whatever reason, and it is never the same amount of time. Swapped blue relays, which did nothing.

[heinzboehmer]

Single red wire being X64101? You mentioned that disconnecting it turns off the relay. That plug powers the DME, so if the DME is off then the signal to the relay is gone too and makes it turn off. Try unplugging X60002, relay will probably turn off since that also removes the signal to it.

Have a spare DME to swap in and test? Otherwise maybe some wire got pinched somewhere and is causing the signal to the relay to stay on.

[sapote]

Gents, I noticed that my switched 12v to the fuse box in the engine bay, and subsequently to the dme via the blue relay, stays on after the key is out.

Should have given more reference to this switched 12v signal, as all said fuses are turned on/off by the DME relay (you referred to it as blue relay?)

[sapote]

I had power at the single red wire coming from inside the car which drives the blue relay inside the engine bay. There are 3 switched 12v coming into the fuse box upfront. The single plug one is the one that stays on for whatever reason, and it is never the same amount of time..

The red wire input to the relay K6300 in the wiring diag above, is always 12v un-switched, so it's normal, unless you're talking something else.

[smee123]

I will swap look at x60002. And try a different dme. The problem isn't consistent enough to point to one or the other but that relay stays on.

[smee123]

I will check voltage also when the car is running. Maybe the alternator is smoked and it's not enough voltage to switch the transistors, although I doubt that.

[smee123]

Voltage is steady at 14.19v. Second dme does the same thing. Keeps the relay energized after key is out of the ignition. Pulling x60002 turns the relay off, but comes right back on when I plug x60002 in. Pulling x60001 resets turns off the relay and the dme. Does not come back on when x60001 is plugged back in. Wire from the dme x60002 to relay coil is continuous and has no resistance.

[smee123]

I think the issue might be in x60004 coming from the car. The ms45.1 has slightly different wiring than the mss54, however, I removed the wiring that did not correspond, specifically pin 5, 15, 19. I moved pin 28 to pin 34, pin 2 to pin 18.

[smee123]

For reference, see below excel for the differences. I wonder if not having a ground on pin 5 on x60004 is causing the transistors inside the dme to go nuts and not drain

https://docs.google.com/spreadsheets/d/1nb05FHMhyj-D8jDaItzYY0pR7mE7QNsU/edit?usp=drivesdk&ouid=115794718397969075282&rtpof=true&sd=true

[heinzboehmer]

Sounds plausible that that ground is messing with things. Pretty easy to check too.

A while back, I built an adapter harness for smog and missed a ground (in X60003) and the car was going nuts. Took a while to figure that one out.

[smee123]

I added a ground on pin 5. No change. I ran to the dealer and picked up am ignition switch. That could manifest like this also. I couldn't find anything concrete that said that pin 5 on x60004 is actually populated. It does close to ground when the ignition is on however.

[heinzboehmer]

I couldn't find anything concrete that said that pin 5 on x60004 is actually populated. It does close to ground when the ignition is on however.

It is:

[smee123]

I will terminate that ground but it made no difference. I think it's the ignition switch. Having that pin grounded didn't solve it. Will put the new switch in tonight.