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Apologies if I have missed it but I've gone thru the site using the search feature and I can't find a simple guide to using the computer on my 75, I can't even reset the Trip 2 counter, just the trip! I'm not keen on hacking it or unlocking the hidden features, just want to know how to use it! Anyone help?
 

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Using the button on the end of the stalk, scroll through the options.

Think it goes:-

Trip 2
Range
Average MPG
Average Speed
Speed (as in what speed to warn you at that you are exceeding it)

Then it goes off with the next press.

To reset either Trip, Average speed or Average mpg, scroll through to the desired option, then press the button again and hold it in. I think 2 seconds it will reset. You then press again to skip to the next function and so on.
 

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Apologies if I have missed it but I've gone thru the site using the search feature and I can't find a simple guide to using the computer on my 75, I can't even reset the Trip 2 counter, just the trip! I'm not keen on hacking it or unlocking the hidden features, just want to know how to use it! Anyone help?
Frankly there is not a lot you can do with it !! Its just a bit of fun when your are bored and stuck in traffic.

Functions - 5

Trip2
Range (Can not reset)
MPG
Average speed
Speed limit Warning

To reset get to the feature you want then press and continue to press the end of the stalk until readout zeros.

The speed limit warning is set in the same way. Get to the feature, then press stalk again and hold until it shows the speed at which you want the warning to go off. Release stalk. To cancel just keep the stalk pressed until the reading is 0.

A lot of us have found that the readouts, particularly MPG are a bit optimistic. Mine always read about 4.5 MPG optimistic. eg real life fill to brim, drive for a week, refill tank to brim, note miles run. Divide miles run by gallons
filled up with = MPG. In my case usually about 27/28 MPG. Computer would tell me 32 MPG !!

And thats about it.

How are getting on with your fuel tank by the way ??
 

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Discussion Starter #6
Frankly there is not a lot you can do with it !! Its just a bit of fun when your are bored and stuck in traffic.

Functions - 5

Trip2
Range (Can not reset)
MPG
Average speed
Speed limit Warning

To reset get to the feature you want then press and continue to press the end of the stalk until readout zeros.

The speed limit warning is set in the same way. Get to the feature, then press stalk again and hold until it shows the speed at which you want the warning to go off. Release stalk. To cancel just keep the stalk pressed until the reading is 0.

A lot of us have found that the readouts, particularly MPG are a bit optimistic. Mine always read about 4.5 MPG optimistic. eg real life fill to brim, drive for a week, refill tank to brim, note miles run. Divide miles run by gallons
filled up with = MPG. In my case usually about 27/28 MPG. Computer would tell me 32 MPG !!

And thats about it.

How are getting on with your fuel tank by the way ??
It's in the garage around the corner from my office at the mo so I was around there a half hour ago - the exhaust comes off all in one piece! and the petrol tank is not as big as I thought it would look - I'm not very technical at all you see! But it looks like it was a big enough job to get to it, doesn't look like a split hose or a leak in the tank itself but a rubber part in a circular filter or breather about 6-8 inches in diameter on the top of the tank, I think it's the pump actually.. He's taking that off to see if it's misaligned or if it'll need a part- if it needs a part then it's gonna be costly- all the labour costs of taking it apart and putting it back together - so hopefully there's a part available if it does need one, I'll leave it in the garage and get a lend of a motor for a day or 2... Oh please let this be the last thing to go wrong!
 

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There is a good chance of it not being expensive if its a sealing ring. The filter can be little tricky to get in apparantly and sometimes the sealing rings can get pinched when your doing it.

If it is the filter (or pump) just not fitting properley cured by refixing or a new seal you could ask why it was not approached from above by taking the rear seat out rather than moving things underneath.

As you know the fuel filter can come apart and I think its about 45 mins start to finish to lift seat, srew filter together and replace seat. A seal should not be a lot different.
 

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Frankly there is not a lot you can do with it !! Its just a bit of fun when your are bored and stuck in traffic.

Functions - 5

Trip2
Range (Can not reset)
MPG
Average speed
Speed limit Warning

To reset get to the feature you want then press and continue to press the end of the stalk until readout zeros.

The speed limit warning is set in the same way. Get to the feature, then press stalk again and hold until it shows the speed at which you want the warning to go off. Release stalk. To cancel just keep the stalk pressed until the reading is 0.

A lot of us have found that the readouts, particularly MPG are a bit optimistic. Mine always read about 4.5 MPG optimistic. eg real life fill to brim, drive for a week, refill tank to brim, note miles run. Divide miles run by gallons
filled up with = MPG. In my case usually about 27/28 MPG. Computer would tell me 32 MPG !!

And thats about it.

How are getting on with your fuel tank by the way ??
As the electronics are BMW, there is a procedure for adjusting the MPG readout so you are able to get the MPG and therefore range to be spot on.

Let me know if you want to do this and I will dig it out and post it up. It is exactly the same procudure as for the E39 and E46 5 and 3 series.
 

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OK all BMW instrument clusters and associated systems have a diagnosis mode/service mode, 75 and ZT included.

From here you are able to alter the calibration factor for the fuel consumption measurements, meaning you can get the OBC to read spot on with the ACTUAL consumption, which in turn gives a more realistic range.

There are lots of other nice things in here, such as an option for doing a service reset, instrument cluster test (all indicators lit and needles moving), instantaneous fuel consumption in litres per hour which you could have on while driving, actual speed, not speedo as speedo is set to over read, engine RPM, engine temp in digital, distance and fuel used since last reset, software revisions, VIN information, fuel remaining in each tank in litres (saddle tanks) , good for fuel pump diagnosis, etc.

To access the diag mode, put the ignition onto pos 0 and hold the trip reset button which protrudes from the cluster, while holding the trip reset, turn to pos 2.

You will see the orange mileage display will display t_est or something. To access some of the functions, including the recalibration of fuel, you need to unlock the cluster.

If you do not start cycling within a couple of seconds, the display will revert to normal and you will have to go again.

So, once you have turned to pos2 and the display reads test, start pressing the trip button and you will see it will cycle up through 1 .. .2 . . . .3. . . .4 etc. Go to 19 and let go of it.

The same principle applies for all modes. You get to the one you want and stop, after a couple of seconds, the cluster "drops" into that mode. You can then use the trip reset button to cycle through the sub menus in each mode.

So, we are at 19, unlock, after a couple of seconds, it will flash unlock . . . . lock. . . . .. . unlock.

Press the trip reset on unlock and it will go back to zero. The cluster is now unlocked for this session. It will lock again when the ignition is switched off. If you just want to adjust the MPG correction factor, now go to 20 and let it "drop in" to this level. Then look down to the bottom of the post for the explanation about mode #20.

Press the trip reset the desired number of times to access the function you require. I list them below:

Rest taken from a BMW forum: When they talk about pressing reset to enter a mode, this is as they have two buttons sticking from the cluster. For us, we simply wait and it "drops into" the mode as I explained above.

TEST-NR. 01
FGSTNR: GM615xx (VIN serial number, censored)
K: 7744
BMWTNR: 8387061
CI:12 DI:06 BI:09
DAT: 43/98 (week and year of manufacture)
HW:04 SW:1100/1100
ZYL:08 M:4 S:4095 (cylinders, and what else?)
CAN:02 AEND:14


There's a lot of information here. You'll notice here that the OBC's native language is German—"cylinder" is represented by ZYL because that's the abbreviation for the German word "Zylinder". You'll see other examples below of German words and metric units appearing in these OBC displays, regardless of what language the OBC usually uses to communicate with you.

At first, tests 01 and 02 are the only test you'll be able to access. The rest of the tests are normally locked. Test 02 is simple:

TEST-NR. 02
(Instrument test)


This test works only when the key is in position 1, NOT when the car is running. Press Reset and all of the gauges and lamps in the instrument cluster come to life. All the lamps except for the warning indicators (such as overheating and low oil) come on. I presume the "idiot lights" are connected directly to their respective sensors so they still work even if the OBC dies.

The speedometer and tachometer move on their own from one extreme to the other, so if you want to get a picture of your speedometer reading 155 without leaving the garage, this is the way to do it. (This is not how I made my autobahn video, though. :)

If you press the Check button to advance to test 03, then hit the Reset button, the indicator will display "LOCK: ON". This refers to a lock function that will keep you out of most of the remaining tests.

To unlock these tests, add up the last five digits in your VIN number, producing a number from 0 to 45. With "LOCK: ON" displayed, hit the Reset button again. The display will change to "LOCK: 00". If the VIN sum was 0, press Check. Otherwise, press Reset until your VIN sum is displayed, then press Check. Press Check again until you get back to test 03. You'll know you got it right when you press Reset at this test and get the following displays (or something like them):

TEST-NR. 03
SI-L: 0610
SI-TAGE: 0000


I assume these have something to do with the Service Indicator function. Maybe there's a way to reset it from here? I've read that the service indicator timer uses fuel consumption rather than miles or time.

I'm told the SI-L reading indicates the number of liters consumed since the last service. On my car, it's too high to refer to liters consumed—by a factor of two or so—unless there's some starting offset. I'll keep track of it for a while and see if I can figure it out.

On this basis, SI-TAGE should be days since the service indicator was last reset.

Here's the rest of what I saw. Note that I've replaced some of the numbers with X's where they can vary according to the operation of the car. Test 04, for example, has two displays related to fuel consumption.

TEST-NR. 04
VBR: xx.x L/100KM (mileage)
VBR: x.x L/HR (fuel consumption in liters/hr)


This test shows the current rate of fuel consumption—think of it as a digital version of the mileage gauge. Someone was recently wondering how quickly his car consumes fuel while idling—mine reports 1.3–1.6 liters per hour, or about 50 hours of idling on a full tank.

TEST-NR. 05
RW-VBR: xx.x L/100KM (average mileage)
RW: xxx KM (range)


I get about 14.3 miles per gallon overall, but your mileage, of course, will vary. :)

TEST-NR. 06
TNK: 7.5/31.0/38.5L (current fuel levels: left, right, total)
TNKANZ: 39.4L PHASE1 (average total fuel level)


This test relates to the fuel tank. I left the numbers in to assist with the explanation, but you'll get different numbers. The first two numbers seem to be independent fuel-level measurements; the third is the sum of the first two. My car has some kind of "reserve" gas tank with a rated capacity of "approximately 10 liters", so maybe the first number is the reserve tank. The first two readings bounce around a lot when the car is moving, suggesting that the fuel-level sensors respond fast enough to show the fuel sloshing around in the tank.

The first value also starts out higher than it ought to be and declines over the first ten minutes of operation to a stable value. The second number starts out low and increases, while the third number remains relatively stable but still moves around. For example, on my first trip after making these measurements, the TNK values started out at 19.6/19.7/39.3 and declined to 6.9/31.2/38.1 within a few minutes. I assume the dashboard fuel gauge ignores the first value as long as there's fuel left in the main tank, since it seems fairly consistent from one trip to the next. I've had trouble with my OBC being overoptimistic about its driving range estimates right after the car is started when the tank is near empty, though, and I think this shows why.

The German word Anzahl means "quantity". The TNKANZ value seems to indicate the average fuel level over some period. And what does PHASE1 mean?

TEST-NR. 07
KTMP: xxx°C (engine core temperature)
N: xxxxx U/MIN (engine RPM)
ATMP: +xx.0°C (ambient temperature)


It was 65°F when I took these readings (about 18°C) and the core temperature stabilized at about 108°C, which seems about right. My car idles at about 500 RPM, a value which is difficult to read precisely from the tachometer.

TEST-NR. 08
V: xxx KM/H (current velocity)


TEST-NR. 09
VB: xx.x V (battery voltage)


Tests 08 and 09 have just one display each, and both are somewhat useful. My battery voltage, idling in the garage, was around 13.5 V.

TEST-NR. 10
LAND: 02 US (country of sale?)


TEST-NR. 11
EINHEIT 1: F7
EINHEIT 2: FA
EINHEIT 3: 4A


Einheit means "unit". Units 1 through 3, then, and each seems to have a hexadecimal (base-16) number associated with it. Intriguing, eh? It gets better later on.

TEST-NR. 12
VANK: xxx.x KM/H
ANK: --:--


On my car, VANK was 077.6 KM/H. Could ANK be from the German word Ankunftszeit for "time of arrival"? That would explain why it was blank, since I didn't have a destination programmed when I read out these values. In this case, VANK could be average speed for the purpose of calculating time of arrival, left over from the last trip.

TEST-NR. 13
GONG?


This one is the audio equivalent of Test 02. Instead of testing the lights, it tests the sounds. You'll hear, in order, the tones for the Memo, Outdoor Temperature Alert, Limit/Code, and Check Control chimes.

TEST-NR. 14
DIAG: 1 C7 81 000
DIAG: 2 00 00 000
DIAG: 3 00 00 000
DIAG: 4 00 00 000
DIAG: 5 00 00 000


These would presumably change if your car has accumulated diagnostic codes for some failure. I don't know what C7 81 means; I've seen my car do the occasional strange thing, but nothing bad has happened. At least as far as I know.

Now, here we get into the most intriguing test:

TEST-NR. 15
PORT A00: xxxxxxxx
PORT A01: 00000111
PORT A02: xx0x0001
PORT A03: 00000011
PORT A04: 000x0101
PORT A05: 001B1111
PORT A06: 00110101
PORT B00: xxxxxxxx
PORT B01: 00100010
PORT B02: xx0x0110
PORT B03: x0111001
PORT B04: 000x1111
PORT B05: 11100111
PORT B06: 00000000


Here we have some cool stuff. These appear to be register values from some type of microprocessor, displayed in binary. The 0's and 1's showed here were stable when I read out these values; the x's were toggling between 0 and 1. I didn't take any time to try to figure out what these bits mean, with one exception:

Notice the "B" in register A05—I discovered that this bit is connected to the button on the turn-signal stalk that controls the on-board computer (OBC) displays that normally appear in the check control indicator. Normally this bit is 0; press the OBC stalk button and it goes to 1.

TEST-NR. 16
OELTEMP: -48°C


This means "oil temp," but I'm pretty sure the oil was a lot warmer. In fact, I'm pretty sure there isn't anything on my car that can be this cold. So it's a mystery.

TEST-NR. 17
RCC-EMPF.: ----MIN


I have no idea what this means.

TEST-NR. 18
(No response to Reset on this test.)


TEST-NR. 19
LOCK: OFF (press Reset to turn the lock back on)


TEST-NR. 20
KVBR: 1000


This "test" is actually a way to adjust the OBC's fuel consumption factor. There's a sensor in the fuel injector system that indicates fuel consumption back to the OBC. This "KVBR" value is used to calibrate that sensor using the following process:

Reset one of the OBC mileage indicators and the trip odometer, and fill your tank.
Record the actual fuel consumption for your car over a long period (one to two months at least).
Divide this reading into the trip odometer value to calculate your actual mileage.
Divide this result by the OBC indicated mileage over the same period and multiply by 1000.
You now have your fuel consumption factor. To enter the factor into the OBC, get into Test 20 and press Reset. This will start the KVBR value counting down. It will count down to 750, then start over at 1250. A crude user interface to be sure, but it works.

You probably don't need to change the KVBR value; the default value of 1000 should be accurate. And if your calculated fuel consumption factor is outside the 750–1250 range, there's probably something wrong.

TEST-NR. 21
RESET?


Be careful here too—I didn't try the Reset button on this one, because I assume it resets the whole OBC. This could be a very bad thing.
 
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