Fuel Pump Relay 9434225 Examinations 1998 v70 non turbo

[MrAl]

The power is only applied with the key on for that circuit, but with the jumper in place, the pump runs continuously until the key is back at position 0.
The ignition interlock is mechanical, you have several issues going at once here. A sticky button on the shift knob can be a possible cause.

Hello again,

Ok so i guess then the pump runs continuously without the jumper when everything is working right?

For the ignition and shift know lockup, that's too much of a coincidence.
Both the ignition key got stuck in the ignition and the shift knob got stuck at the very same time that the car would not start, then later when the car would start again, both the key and the shifter worked fine again. That's just too much of a coincidence to be unrelated.

Also, if the ignition key and shifter were mechanically connected, what could possibly connect them together if it was purely mechanical?
It would have to be some lever or cable (similar to the hood release cable). Is there such a thing on this kind of car?
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[abscate]

The key and shifter are connected with a cable. Lets save that for one of the existing threads on that system, as it isnt fuel pump relay related at all.

The new forum software ejects the warp core after six pages, so we are getting close to that, unless Matt puts in the over-ride code.

[MrAl]

The key and shifter are connected with a cable. Lets save that for one of the existing threads on that system, as it isnt fuel pump relay related at all.

The new forum software ejects the warp core after six pages, so we are getting close to that, unless Matt puts in the over-ride code.

Yes ok, but my question really was why did the two lock up at the same time that the relay possibly quick working. There has to be some connection between the two, and i dont mean between the shifter and key (although that is present too as you said and thanks for that too) i mean between the relay (or other engine problem) and the shift/key issue, especially since the two freed up right after the engine started working normally again. That made me think of some sort of immobilizer mechanism. Let me itemize this chronologically:

1. Car runs for a few seconds, then stalls.
2. Car stalls, key jammed in, shifter cant shift out of park.
3. 45 minutes or so later, car starts, key comes out ok, shifter works normally, car runs for 15 minutes no problem.

So at the same time that the car stalled the other two things caused a problem also, then when it started again those two things were ok also. Cant figure out why if the relay went bad, then why would the other two things lock up. I'll ask about that in another thread, thanks.

BTW thanks much for all the info and suggestions really the members here are probably the only people who know anything about this stuff (ha ha).

[abscate]

All of the control magic is on pin. 4 of the fuel pump controller. That maps directly to pin B45 on the ECU via the CBus. The ECU gives some sort of signal on pin 4 to turn. The fuel pump on.
Everything else on the relay is just conventional relay- like.

It would be cool to pull the controller and see what that pin 4 does on key on

[MrAl]

All of the control magic is on pin. 4 of the fuel pump controller. That maps directly to pin B45 on the ECU via the CBus. The ECU gives some sort of signal on pin 4 to turn. The fuel pump on.
Everything else on the relay is just conventional relay- like.

It would be cool to pull the controller and see what that pin 4 does on key on

Hi,

On my car the ECU control signal comes in on pin 31b of the relay. Pin 15 gets turned on by some main relay, pin 87 goes to the fuel pump and must be made +12 volts to get the pump to run, and pin 31 is ground which is the negative battery connection.

From what i see so far, pin 31 stays at ground for all time, never opening up.
When the key is turned to second position to start the car (dont think this happens with the first 'on' detent with the turn of the key) pin 15 becomes active with +12 volts, which powers up the circuit dont know if it turns the pump on yet but i dont think it does yet.
Then guessing only from the schematic so far, the ECU supplies +12 volts to pin 31b which starts the pump running.
Not sure yet what happens after that. Of course i would expect the pump to keep running and so i think the ECU signal on pin 31b has to stay positive +12 volts, but it could be a pulsing signal. I have to see the signal to be sure which i havent done yet.
I hope to get out there soon with the test equipment to see what the ECU signal does, and that will tell all i think.

LATER
Oh i see what pins you were referring to, on the large wiring diagram of the entire car:
Pin 1 is pin 15 on the relay itself.
Pin 2 is pin 31 on the relay itself (continuous ground which is the negative battery connection).
Pin 3 is lead to fuel pump pin 87 on the relay itself (fuel pump power lead).
Pin 4 is the lead from the ECU pin 31b on the relay itself (signal to the relay circuit).

[abscate]

31b will be grounded at the ECU to enable the controller

DIN standard for 31b is ground through switch , in this case , ECU

[MrAl]

31b will be grounded at the ECU to enable the controller

DIN standard for 31b is ground through switch , in this case , ECU

Oh ok thanks i guess i had it backwards. I'll look into this more in the coming days too.

Oh BTW, i found another important capacitor on the board. It's a 1uf i think 35 volt ceramic. Those kind last longer though so maybe it's ok.
There are other smaller SMD capacitors too but they are probably just there to prevent noise from interfering with the signals.

[abscate]

I’ve got those caps sitting on my desk up North if you get the urge to recap…..

[850oldschool]

Reading this thread I'm reminded of a small discussion a while back which revolved around the fact that the relay and fuel pump often fail in tandem. I think the theory was advanced that as the relay declines and no longer holds the contacts solidly closed the resulting transients cause the pump to deteriorate, although it could also be that as the pump ages and pulls more current the operating temperature of the relay increases.

I'm wondering if you could predict failure by using an oscilloscope to look for noise in the relay output.

[abscate]

I think the tandem failures are more likely misdiagnosed repairs and parts swaps, affectionately called

“ firing the parts cannon”

Or

Swap-Nostics