Transmission Failure after F1 relay change.

[CatmanV2]

Are the relays switching with the control signal? You should be able to feel them switch, or check the output for voltage.

If the F1 *relay* is stuck on, then your pump will run no matter what voltage is applied to switch it.

If the F1 relay is switching off and the pump is still running, something very odd is happening.

The F1 should be controlled by the pressure sensor. i.e. pressure drops, relay closes, pump runs.

So pump on all the time=
Duff relay (stuck on)
Duff pump (no pressure building)
Duff sensor (not reading pressure is built up)
Low fluid (Low pressure)
Leak (low pressure)

Personally given it won't shift into gear, I'm leaning to no / mis read pressure.


C

 

[Gixerboy]

My money is on the Pump, motor is not providing enough pressure to allow the actuators operate.

Trust you get to the bottom of it

Cheers

 

[jluis]

I've just done a thorough check of both relays with a multimeter. Both are receiving signal and switching as expected. Weird thing is I can hear the F1 pump running but it never shuts off so definitely seems like there's something else wrong. As it happens the car is booked in tomorrow to have some work done that was outstanding from when I bought the car, so I'll probably get it recovered there so they can have a look at it. I'll let the forum know how it turns out.

Do you hear the pump running as it used to before?
It's unlikely but your relay might be inducing parasitic resitance on the circuit therefore limiting the current the pump gets leading to insufficient power to raise pressure to the normal level.
You also mention the relay control voltage is 10V. That sounds a bit too low. Have you checked the state of your batery?
If it doesn't have enough juice, it won't pressurize the system.

 

[HowardM]

Firstly, many thanks for the all the suggestions I've received so far.

During my investigation I buzzed out the wiring of relays R22 and R23. I've drawn it up and attached it as a pdf. Just to recap my owners manual describes the relays as follows:

R22 - F1 pump
R23 - Rear connected devices 1 (controlled by NVB)

Also, the fuse MF70 is described as being for the F1 pump but in fact feeds R23 not R22 (see my diagram).

So, I think I agree with one of the links that spkennyuk pointed me at that it is not quite correct here's why:

With Ignition off (key out) and the drivers door closed here's what I see on the relay ctrl and output terminals:

R22: ctrl = no signal, output = 0v
R23: ctrl = no signal, output = 0v

And of course I can't hear the pump running.

With Ignition off (key out) and the drivers door open I see this:

R22: ctrl = present, output = Battery voltage
R23: ctrl = no signal, output = 0v

But I still can't hear the pump running.

With Ignition on:

R22: ctrl = present, output = Battery voltage
R23: ctrl = present, output = Battery voltage

And ! can now hear the pump running.

So given that MF70 feeds relay R23 and I can only hear the pump running when this relay has switched it would seem that in fact R23 is the pump relay and not R22.

Hopefully someone may find the above useful in the future. Meanwhile I think I can conclude that my problem is not with the relays and I'll therefore need to get the codes read.

 

[VMSRTI]

Couple of questions!

Was ignition off/ key out Emgine in N when you changed it?
Have you checked the relay terminals are actually making contact with the spade connections?
Have you disturbed the adjacent relay because this supplies the control signals to the coil terminals for the F1 relay?
As with most things I'm sure it will be something simple,.
On my car the pump became a bit sluggish, & although could be heard running, was not developing enough pressure. This brought up the Red Gearbox light.

So if you can hear the pump prime when you open the door, that kind of proves the relay is working, if not enough pressure, that would stop it shifting.

Cheers

curious to know why it has to be in neutral. Not sure what mine was in when I changed it sometime ago but gave no thought to this.

 

[drewf]

Here are the 6 pages of the workshop manual for the M138 CC gearbox wiring:

 

[HowardM]

Currently trying to get the car recovered to have the transmission problems looked at, but Green Flag are throwing a wobbly because the car is stuck in gear and our driveway is just dirt at the moment (house under construction). Does anyone know if there's some way to get the car into neutral, even if it involves getting under the car?

 

[CatmanV2]

I can't think of one

Surely this should be Green Flag's problem?

C

 

[HowardM]

I can't think of one

Surely this should be Green Flag's problem?

C

They sent a low loader yesterday but were unable to get the car on there. I thought they were sending something to lift it on this morning but just had a call to say that's not happening and they're sending a technician out to assess the situation. I think we're going to end up with the crane anyway!

 

[CatmanV2]

They sent a low loader yesterday but were unable to get the car on there. I thought they were sending something to lift it on this morning but just had a call to say that's not happening and they're sending a technician out to assess the situation. I think we're going to end up with the crane anyway!

Indeed. This can't be the first time they've had to deal with a non rolling car!

C

 

[jluis]

Did you already found out what the problem was?