tachometer-rpm and odometer

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atlanta
#1
Just bought 1988 325 and the rpm-tach doesn't work any suggestions on where to start to find problem?Maybe a Fuse or cable? Bought Haynes manual but no help.....Thanks
 

epj3

Senior Member
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Lancaster, PA
#3
Probably the battery or the fuse, like big daddy said.

I would SERIOUSLY reccomend getting a Bently manual, it is much much better than the Haynes.
 
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Location
Kansas City, MO USA
#4
Hmm,

If the service interval lights will not reset you will need to replace the SI board batteries.

The batteries provide a counter to the sender signal, if the battery is dead the signal will exit through the battery and not the indicator.

SI reset and batteries

With the ignition switch at (position two) and the engine not running, grounding pin seven #7 of the diagnostic connector to pin one #1 for approximately three (3) seconds will reset the oil service lights. Grounding pin seven #7 to pin one #1 for approximately twelve (12) seconds will do an inspection service reset.

More information.

http://www.specialistcarsbmw.co.uk/stevenage/service/service_lights.htm


http://www.unofficialbmw.com/images/reset1.gif


1. Ground
4. Temperature sensor
7. Reset
8. TDC sensor yellow
9. TDC sensor shield
10.TDC sensor black
11.Start signal
12.Alternator charging excitation voltage
13.Ignition coil
14.Alternator charging supply current
15.Oxygen Heater

It will signal an oil change need between 5k and 7k depending on your indicated speed since the last reset. It will signal stealer inspections at all the predesignated miles.



http://www.eskimo.com/~dalus/bmw/e36/electrical/e36_reset_service_lights.html




SI Board Swap Out

Last but not least - the SI Board. Above is a new SI Board with lithium batteries and below is the old one. Note the blown battery on the old SI Board (green circle). The light blue rectangle shows the actual service indicator LED's which appear on your dash display. These LED's are mounted on a separate circuit board which must be pulled out of the old SI Board and plugged into the new one. This is an easy task. The purple arrow shows the orientation of the SI Board relative to the driver.


If it fails to reset then you need batteries.

Varta battery 500RST OE part.

Radio Shack: part number 23-191: $6.49 for set of two; they come w/solder tabs on them.

1.2 volts / 700mAh

Charge fully B4 installation on SI board.

Consider mounting batteries "remotely" under dash, etc. in separate holder for easy removal in future (i.e. not pulling the console out and apart); you can buy a plastic holder at RS. Run leadwires from holder to SI board connections. Makes life easy if you ever need to replace batteries again.

From Radio Shack, get:
1) You'll need a twin AA battery holder ($3)
2) 2 AA NiCAD rechargeable batteries ($6)

Later,

This shows the issue,

 
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Location
Broomfield, CO
#6
KC is it nesacary to replace the whole SI board if the bataries are dead or can you just re-sodder the battaries? You make it seem like you need a new one, just wondering cause my oil service lights wont stay out they are all lit up all the time. As well as the service light. Even after resetting the Comuter.
 
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Location
Winston Salem, NC
#7
Uhh, if you have a 1986 325e, you shouldn't have a service engine light on. The Motronic 1.0 on these cars does not have self-diagnostic capabilities and hence no service engine light.

But, to answer your question, yes, you can just resolder new NiCd or NiMH batteries onto your existing board.
 


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