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Re: M reg 1995 2.1td autobox Swap

Posted: Fri Jan 14, 2022 8:37 am
by citroenxm
Thanks will.. The door interior light push switches do activate the hydractive... As I had to hold one pressed in when emulating a closed door in the end I unscrewd it..

Thank you..

Sorry Chris if I sounded a bit bolshy.. I was tiered last night and slightly frustrated with other things.

Re: M reg 1995 2.1td autobox Swap

Posted: Fri Jan 14, 2022 12:45 pm
by White Exec
No problem whatsoever, Paul. ;)

Re: M reg 1995 2.1td autobox Swap

Posted: Fri Jan 14, 2022 2:57 pm
by citroenxm
Two things have emerged from the fuse box swap..

I'm confident enough to say now that the Ac and cooling fans sticking on when ignition is, switched of is now resolved.. And also the ABS light is now staying out after self test. It would previously either stay on.. Then after a while if I flicked the key to switch the fusebox relays it would go out .. But slow braking would bring it back on. Now.. I cannot get the lamp to come one while in use.

Lexia read the ecu previously and had reported power supply issues to the hydraulic block relay board... Which seems now I found the problem.. So very pleased with those results... I'm not conclusive on the current draw yet. Weekend is here so everything car wise stops while little man is home.

Re: M reg 1995 2.1td autobox Swap

Posted: Sat Jan 15, 2022 4:05 pm
by Dieselman
White Exec wrote:
Thu Jan 13, 2022 5:11 pm
Test it by supplying (off the car) a 5W bulb or a 21W bulb, which should draw approx 0.42A and 1.75A respectively from a known 12v source. A 55W headlight buld should pull approx 4.58A, but that could be a stiff test for some DMM's, and should only be done for 10-15secs max, for the reason below...

DMM's easily get their higher current ranges 'cooked' by mild abuse, when the internal series resistance gets heated up without actually blowing the internal fuse. Also worth checking that internal fuse (and its holder), as, if oxidised, it will affect current readings. All should show up with the test above.
citroenxm wrote:
Thu Jan 13, 2022 5:38 pm
How can a bulb give me a current draw reading.....?

I e since put a new battery in the meter.. Still had 0.300 amp draw in 10amp range. But got that down to 0.113 amps on 10amp range.
I've had chance to read this so will paraphrase to hopefully explain.

What White_exec is saying is that a DMM isn't reading current at all, when used as an ammeter, it is actually a voltmeter measuring the voltage drop across an internal resistance of known value.

You can check the accuracy of your meter by connecting to a known external resistance being fed with known voltage and unrestricted current.

e.g. 12v battery, 5W bulb.

Power = IxV, which extrapolates to P/I = V and P/V = I.

Using I = P/V.
P = 5W
V = 12v.
5/12 = 416mA, or 0.42A

One can test the accuracy of their Dmm by checking the current flowing through a set of known wattage bulbs.

If the meter has been run close to it's maximum current allowance, or for an extended duration, either the internal shunt, or the switching may have overheated and changed resistance, so the meter might give incorrect readings, hence testing against known values (various bulbs of known wattage) can be used as a check of the meters accuracy (calibration).

If you don't have a working ammeter, a voltmeter and load of known resistance will give voltage drop values, which can be converted into Amps flowing through the circuit.
This is how measuring voltage drop across the fuses detects current passing through a circuit. The fuse has a small resistance, so any flow of electricity causes a voltage drop. Even a piece of wire has some resistance.
If there is no current flow, no voltage drop occurs.

This negates the need to pull fuses out, which is advantagous on cars that use CAN, as they take upto 30 minutes to shut off again once the module has been activated, which it will be by pulling out and replacing a fuse.

Your meter appears to have a 10A input and also a mA input for current readings less than 1A.
Typically the more sensitive selection will be more accurate for the very low readings. Do not test a current of more than 999mA through the sensitive input, or the meter will be damaged.

I've not tried this on a circuit containing components and current leakage, only on checking continuity of power supply, or Gnd, but it means that if one didn't have a Dmm to check for current leakage, a selection of bulbs could be used.
A circuit passing 0.4A, will illuminate a 5W lamp, but not a 21W lamp.
The risk is the lamp itself will provide resistance which may restrict current flow enough to stop illumination.
12v, 5W lamp has 28 ohm's resistance.
12v, 21W lamp has 6.9 ohm's
12v, 55W lamp has 2.6 ohm's
12v, 1W lamp has 144 Ohm's resistance and will draw 83mA of current, which is enough to drain the battery fully in 35 days, so no start after about 18 days.
iirc, your draw is currently about 100mA, so should be enough to illuminate a test lamp, or dashboard warning bulb.

Re: M reg 1995 2.1td autobox Swap

Posted: Sat Jan 15, 2022 4:21 pm
by citroenxm
The abs light out was short lived and not relayed to the fuse box change... But with lexia is returning a rear off side intermittent sensor fault although it still reads.

So will get into the hub sometime and look for dry grease, and also check the connection between sensor and car loom.

Re: M reg 1995 2.1td autobox Swap

Posted: Sun Jan 16, 2022 8:39 am
by Dieselman
If the Abs fault occurs before the car has moved it is the sensor/wiring connection. Probably the connector on the rear subframe.
If the lamp only illuminates after the car moves it is likely to be the sensor not reading the reluctor ring.

These are passive sensors so generate a small sine wave, AC, voltage as the wheel spins.
This can be checked at the sensor connector using a Dmm, or oscilloscope.

Re: M reg 1995 2.1td autobox Swap

Posted: Sun Jan 16, 2022 9:46 am
by White Exec
Sensors are around 1050ohm each, if iirc from some posts of John's - but do check.

Re: M reg 1995 2.1td autobox Swap

Posted: Thu Jan 20, 2022 10:51 am
by citroenxm
OK. Just going back to my current draw. I've now got it to 70ma

I discovered the box for the dab digital radio was drawing the amps... so left it disconnected for now..
IMG-20220120-WA0000.jpeg
I'll leave it at that for now.

Re: M reg 1995 2.1td autobox Swap

Posted: Fri Jan 21, 2022 7:23 am
by Dieselman
No surprise there, it's usually aftermarket add-ons that create parasitic draw.
Did the DAB module have a constant live feed, if so, is it meant to? Is there any reason it couldn't just be fed with Ign fed live, or does it use volatile memory to hold the stations?

70ma is the same as a 0.8w lamp being active constantly.
With a good condition, charged, 760ah battery. it should take 10,800 hrs to discharge fully, so about 226 days before the car won't start.
Internal battery leakage will reduce this.

It would be interesting to see how low you could make any current draw, though, you have already ensured the battery won't prematurely lose charge.

The mA input on your meter appears to be 200mA maximum, so now the draw is safely below that, it would be interesting to see if that scale gives the same value reading. It should be more accurate given it is calibrated for greater sensitivity.

Re: M reg 1995 2.1td autobox Swap

Posted: Fri Jan 21, 2022 2:56 pm
by citroenxm
I don't know about its memory I think it keeps it like the radio as it sat 2 years with no battery on and when I did switch it on it came up on radio 2 I think.. I thought about putting it on a switched supply.. but for now it will get the ultimate weekend test now as xm hasn't been used since yesterday 4pm. And I don't think I'll use her again till Monday..