P38A Height Sensor replacement

UnitLandy · Friday at 14:47

Sadly, I don't have him anymore but new Daleks are in the pipeline...

pwood999 · Friday at 14:47

Measure the resistance at the height sensor. Then re-connect, and measure the same wires at the ECU. There will be small differences, but any open circuit wires should show up. Then decide whether the take seats out, carpet up, or just run new wires !!

cornishboater · Friday at 14:48

pwood999 said:
Cruise pump uses LH connectors - see picture.

RF footwell white connectors (C101 & C102). Just search RAVE for these two (Control F3 & search).

Cruise wiring (except pump)
Various ECU diagnostic connections
Brake Switch
Some of the HEVAC stuff
Some of the Instrument wiring
Etc. Etc.

Thanks, I believe it may have been you that mentioned that the inhibit wire also ran through there, I have printed the diagram so I will have to dig it out. As I was only looking for the inhibit I probably didn't notice the cruise circuit.....

cornishboater · Friday at 14:49

UnitLandy said:
Sadly, I don't have him anymore but new Daleks are in the pipeline...
View attachment 319794

where did you get them, I gotta know..........

cornishboater · Friday at 14:54

pwood999 said:
Measure the resistance at the height sensor. Then re-connect, and measure the same wires at the ECU. There will be small differences, but any open circuit wires should show up. Then decide whether the take seats out, carpet up, or just run new wires !!

I have a long tester unit and I went directly from the ECU to each sensor which told me there was no continuity on the RH rear which was all well and good but it didn't obviously tell me where the problem was. After tons of wire wiggling I pinpointed the break and all was well with the world again. I hindsight it would have been far easier just to have run a new wire and left the old one there, such is life!

marjon · Friday at 14:54

UnitLandy said:
Sorry I said CPU instead of ECU. My bad. So I'll just have to follow the cables back until I find the right ones...

I am not going to get to involved as others know more than me. But. Unplug it at the sensor and the ecu, bridge the relevant pins at 1 end and check continuity to start with. Continuity isn't always the be all of tests but its a start.
Then check the "common" line.

Or you could do each line separately.

Were they good quality sensors?

You can check the sensor on its own to see if its ok with a DMM, which I assume you have, if you don't then get 1.

J

UnitLandy · Friday at 14:54

Well these aren't mine I have to say. They belong to a friend of mine who builds them for people. I can give him your details if you want one

.
I build my own too to high standards as per the original but my workshop is in the works lol.

pwood999 · Friday at 14:55

EAS Door input is on Pin-34 on C117. Look for PO wire (Purple / Orange Stripe).

UnitLandy · Friday at 14:56

marjon said:
You can check the sensor on its own to see if its ok with a DMM, which I assume you have, if you don't then get 1.

Ooow. Where do you get those and what's it's full name?

UnitLandy · Friday at 14:58

Thanks Lads, BTW! All your input is fantastic. I hope it's helpful to each other too!

marjon · Friday at 15:00

UnitLandy said:
Ooow. Where do you get those and what's it's full name?

Digital Multi Meter

.

You got 1 of them right if you make Daleks

.

What diagnostics you using?

J

cornishboater · Friday at 15:39

UnitLandy said:
Ooow. Where do you get those and what's it's full name?

Bob, or maybe dave.......... You can't own a P38 without a DMM (or a Dalek come to that..) I run a village hall and a dalek would be a great place for a camera to watch over the parties especially if the top was powered (and the exterminator laser)

UnitLandy · Friday at 16:35

Ah yes I have a DMM. What an idiot I am for not realising that, haha. Well like I say, DM me if you would like futher details. They £3000-£3500 a piece so they're not cheap mind you.

Datatek · Friday at 16:39

pwood999 said:
But the height sensors do not go via those connectors !! Soldering C104-C204 and C207-C357 did sort other stuff like these:

EAS timer relay diagnostic trigger
EAS Height Switch
Dodgy audio glitching
Cruise control,
Ambient air sensor
SRS diagnostics

They don't but the ride height switch does and that is what causes the problems often attributed to height sensors.

UnitLandy · Friday at 17:23

Datatek said:
They don't but the ride height switch does and that is what causes the problems often attributed to height sensors.

Ah! Is that a fact. That's interesting. So would the diagnostic still register the sensor out of range if it was a bad connection the height switch?

That would be so much simpler...

Datatek · Friday at 18:00

UnitLandy said:
Ah! Is that a fact. That's interesting. So would the diagnostic still register the sensor out of range if it was a bad connection the height switch?

That would be so much simpler...

Good question to which I do not have a definitive answer

pwood999 · Friday at 19:18

While I agree there could be unexpected behaviour, I'm not 100% convinced it would cause height errors itself.

Unfortunately there not any real info out there that I have found. Nigel Hewitt's page does give some help, no definitive details on the real protocol.

The Up & Down switches from the switch to the EAS ECU are simply grounded to the ECU pins 32 & 33 to tell the EAS to go up or down. The EAS output data signals on pins 7 & 25 tell the switch LED's what to display, plus are inputs to the BECM pins 9+18 for messages in the Instrument Cluster display. Pin 8 on the BECM is for the Wade Lamp in the instruments, but it's not clear if this is triggered by the EAS Data, or thye state of the top LED ?

So issues with C104-C204, and C102-C202 will have different impacts. Up-Down might need several presses to get the ECU to respond ? Intermittent data signals would me with the LED's, and potentially tell the BECM incorrect info.

Maybe between us all we can figure it out ??

Datatek · Friday at 19:43

pwood999 said:
While I agree there could be unexpected behaviour, I'm not 100% convinced it would cause height errors itself.

Unfortunately there not any real info out there that I have found. Nigel Hewitt's page does give some help, no definitive details on the real protocol.

The Up & Down switches from the switch to the EAS ECU are simply grounded to the ECU pins 32 & 33 to tell the EAS to go up or down. The EAS output data signals on pins 7 & 25 tell the switch LED's what to display, plus are inputs to the BECM pins 9+18 for messages in the Instrument Cluster display. Pin 8 on the BECM is for the Wade Lamp in the instruments, but it's not clear if this is triggered by the EAS Data, or thye state of the top LED ?

So issues with C104-C204, and C102-C202 will have different impacts. Up-Down might need several presses to get the ECU to respond ? Intermittent data signals would me with the LED's, and potentially tell the BECM incorrect info.

Maybe between us all we can figure it out ??

View attachment 319841

Corrosion causing tracking between pins causes a variety of problems which I think confuses the ECU.

UnitLandy · Friday at 22:22

More often than not the up down switch lights operate for a few second without incident and the car will be roughly at the right height then all the lights on the switch come on and an EAS fault is read out on the dashboard (along with an airbag fault which is new)

brianp38dse · Friday at 22:50

What diagnostics are you using on the eas to calibrate the sensors

P38A Height Sensor replacement

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