My Motometer speedometer consistently operates when car is going under 35 or 40 mph but drops to 0 when speed goes above that range. Car is 1998 325iX. Sending unit (speedometer pulse generator, BMW Part 62168357020) on final drive cover shows signal of .6 volts at slow speeds where speedo is working that drops to about .45 volts by 35 – 40 mph. Does this indicate a problem in the instrument cluster or in the pulse generator?
It seems to me that if the pulse generator is just a coil of wire encased in plastic that creates an alternating current each time the magnet passes its coils, then it is logical that the voltage would drop gradually as vehicle speed increases the frequency / reduced the duration of the magnet’s interaction with the coil. At the same time though, it doesn’t make sense that the gauge in the cluster works – but only at low speed. Any ideas?
In the interest of full disclosure, six months ago (when I bought the car) the speedo, tach, fuel economy meter and cruise control all worked (I think), but the odometer had stopped. I removed and replaced the odometer gears (Odometer Gears LTD). When I reinstalled the cluster, I couldn’t remember which pin on the green connector (under blue dot on right hand side of Instrument Panel 2.jpg) on the back of the speedometer housing the single wire (blue/yellow) for the cruise control belonged.
The shape of the connector on the end of the blue/yellow wire leads me to believe it is one of the three on the gas gauge side of the green connector (only ones visible on left side of Instrument Panel 3.jpg) but I think I’ve tried each possible pin and cannot get the cruise control to work again. Does anybody know the correct place to plug in the cruise control to the speedometer?
Then I noticed the economy gauge moves to 0 when the engine is running but does not register fuel economy. It returns to the left side (over 40) when the engine is shut off. I think it used to work? I was O.K. with that for a couple of months (I was working on poor running condition. Car ran fine up to about 3500 rpm but above that would backfire and lose power. Sprayed cleaner in AFM and now car accelerates smoothly up to red line … well, as close as I’ve tried to take it) till the speedometer started dropping out over 40 mph about two weeks ago.
Are all these problems related? It isn’t the SI board or its batteries, is it? Okay, maybe the economy gauge as it gets its signal from the SI board, but not the speedometer RIGHT? SI board seems good. Buncha lights were lit when I bought the car in October. I remember distinctly the red SI light being lit. I bought a Peake Research FCX3 R5 BMW Code Reader, checked the codes (bad LAMBDA relay which I unplugged and plugged back in) and reset the SI lights. The SI lights now light (4 green-not far left green, yellow, or red) with ignition on (position 2) then all go off with engine running.
One more question: low fuel light is inoperative. Is it supposed to light (bulb check) when ignition is turned on (position 2)? It does not (bad bulb?).
It seems to me that if the pulse generator is just a coil of wire encased in plastic that creates an alternating current each time the magnet passes its coils, then it is logical that the voltage would drop gradually as vehicle speed increases the frequency / reduced the duration of the magnet’s interaction with the coil. At the same time though, it doesn’t make sense that the gauge in the cluster works – but only at low speed. Any ideas?
In the interest of full disclosure, six months ago (when I bought the car) the speedo, tach, fuel economy meter and cruise control all worked (I think), but the odometer had stopped. I removed and replaced the odometer gears (Odometer Gears LTD). When I reinstalled the cluster, I couldn’t remember which pin on the green connector (under blue dot on right hand side of Instrument Panel 2.jpg) on the back of the speedometer housing the single wire (blue/yellow) for the cruise control belonged.
The shape of the connector on the end of the blue/yellow wire leads me to believe it is one of the three on the gas gauge side of the green connector (only ones visible on left side of Instrument Panel 3.jpg) but I think I’ve tried each possible pin and cannot get the cruise control to work again. Does anybody know the correct place to plug in the cruise control to the speedometer?
Then I noticed the economy gauge moves to 0 when the engine is running but does not register fuel economy. It returns to the left side (over 40) when the engine is shut off. I think it used to work? I was O.K. with that for a couple of months (I was working on poor running condition. Car ran fine up to about 3500 rpm but above that would backfire and lose power. Sprayed cleaner in AFM and now car accelerates smoothly up to red line … well, as close as I’ve tried to take it) till the speedometer started dropping out over 40 mph about two weeks ago.
Are all these problems related? It isn’t the SI board or its batteries, is it? Okay, maybe the economy gauge as it gets its signal from the SI board, but not the speedometer RIGHT? SI board seems good. Buncha lights were lit when I bought the car in October. I remember distinctly the red SI light being lit. I bought a Peake Research FCX3 R5 BMW Code Reader, checked the codes (bad LAMBDA relay which I unplugged and plugged back in) and reset the SI lights. The SI lights now light (4 green-not far left green, yellow, or red) with ignition on (position 2) then all go off with engine running.
One more question: low fuel light is inoperative. Is it supposed to light (bulb check) when ignition is turned on (position 2)? It does not (bad bulb?).
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