Accumulator Health Testing

[bazzbazz]

That means it should not pass the EOL Calibration, correct?

Replace the Back & top sensor (Gear selection & Gear engagement sensor) then do EOL calibration.

Test drive then do clutch calibration.

[Citroënbender]

Thanks Bazz,

As presenting it definitely shouldn't pass the EOL calibration; agreed.

Given there's no "one stop sensor shop" close by, will swapping the sensor positions move the fault to create a different symptom?

It's currently less than ten degrees and raining, hopefully that will improve before I get under the bonnet!

[bazzbazz]

Do any errors come up on diagnostics?

[Citroënbender]

No, none and none in the motor ECU either. 

Checked console lever on parameters and it shows forward, backward, reverse instruction as received, no paddles to check.

Hydraulic pressure seems OK, reporting of pump relay action a bit flaky.

Presently got battery neg off.

[Citroënbender]

Observed that pressure seems to drop very low (36-odd bar) before pump starts, and once pressure is restored the shifts seem OK. Pump doesn't even start automatically when the pressure is this low but takes a while to kick in.

Could this be a faulty pump?

[bazzbazz]

Faulty pressure sensor.

Check & clean connector & sensor or you'll need to cannibalise a working one from wreckers.

Still is not the reason for not engaging odd gears, that will be most likely sensors or loose Pinch Bolt.

[Citroënbender]

The pinch bolt checked out as good and tight. I checked the harness connections to the sensor pots, all seemed snug.

I'd been thinking it may have become a "chicken and egg" situation where a flat sphere was overtaxing an aged pump. Hadn't really considered the pressure sensor.

[bazzbazz]

Understand that, but the pump is supposed to engage at 45 Bar and its condition is irrelevant as to when the pump relay is closed and power is sent to the pump. I have come across this problem before and a replacement pressure sensor always solves the problem, as long as the replacement sensor is in working order of course.

Once the pump has primed, you get 2-3 gear changes before the pump runs again, yes? What pressure does it stop at when repriming the system, should be around 55.

If you are concerned about pump condition use MES to continuously run the pump, this should reveal any issues.

Again, this still is not the reason why it's only engaging odd gear.

[bazzbazz]

had also neglected to tell me that when it was not upshifting the "2" was flashing... 

This indicates and electrical error or some sort.

Just to clarify, have you done an EOL and did it pass ok?

[Citroënbender]

I tried to run another EOL and it failed to proceed after the first fifteen seconds or so. Couldn't do screenshots this morning as the phone went flat...

Pressure dropped faster than I'd expect with a healthy accumulator, two shifts and it was dipping to 42 bar or something. The pump does stop at 55 or so, but there is a fast drop of a bar or more.

I popped the relay cover to manually bridge the contacts and ran the pump up to slightly overpressure, listening to its note. Didn't seem to change appreciably or greatly heat up the contact wafer in the relay.

Will see if the sensor crosses to anything else I might find more readily, there's apparently one other identical car around but I doubt they'd loan me critical parts for a swap test.

[bazzbazz]

2-3 changes is all you will get from a good Accumulator. Time it from full pressure till it gets to 45 bar and let me know.

If the pump runs with every gear change it is cactus.

When you get a chance run the EOL and let me know what errors/faults it shows up.

[Citroënbender]

Thank you again.

I'm trying to cross the sensor, is it P/N 71719383?

Actual work needs to be suspended until Tuesday as my konfetka has a significant birthday this weekend and we're in the throes of mad preparation with a forecast of possible heavy rain... 

[bazzbazz]

"cross the sensor"  . . . . .Huh?   

[Citroënbender]

Meaning, to check the part number for broader applications, as in possibly later variants of Selespeed or actuator assemblies of other marques. There's probably just one other 147 Sele in this one-horse town.

(That said, I do regularly see a black 159 with the personalised plates 159JTS getting around.)

[Citroënbender]

Pressure sensor replaced. Only a minor "douche vert" was enjoyed.

Would appreciate confirmation on two points, please.

1. The PF7C pots are now PF2C
2. Nominal track resistance is 1200 ohms

Thanks!