techometer's mpg gauge question??

[GUERONASTY]

'87 325is

Okay so took my car in to get rear main seal & rear main seal cover & oil pan's gasket replaced, leaking oil. After I got the car back my MPG gauge was not working properly. It reads 5mpg where I'm on it or barley even at 500rpm on any gear. As soon as I let off gas goes to 40mpg when it should be at no reading at beginning of guage. Everything else works. Anybody was this happen to them or has some advise as far as what's wrong or needs to replaced / adjusted???
... I posted under correct forum now

http://www.r3vlimited.com/board/showthread.php?t=233988

[dnguyen1963]

Your SI board/batteries are probably dead. Hopefully, it is only the batteries. Remove the SI board and check for corrosion. If there are a lot of corrosion then most likely you'll need a new board. Check this forum for available used board (a lot cheaper than buying a new one). If you board is in good shape then take it to Batteries Plus and have them put in new batteries for you. New board would run around $135 with core exchange from Pelican. BTW, tighten up the ground nuts behind the gauges when you have the cluster out.

[GUERONASTY]

Your SI board/batteries are probably dead. Hopefully, it is only the batteries. Remove the SI board and check for corrosion. If there are a lot of corrosion then most likely you'll need a new board. Check this forum for available used board (a lot cheaper than buying a new one). If you board is in good shape then take it to Batteries Plus and have them put in new batteries for you. New board would run around $135 with core exchange from Pelican. BTW, tighten up the ground nuts behind the gauges when you have the cluster out.

Thanks guy gonna give that a try?
...Anyone second that or have any other ideas???

[nando]

one post is enough.. anyway, I second the SI batteries. you can also replace them yourself for *way* less than a rebuilt board, but you could also have cracked solder joints and other issues that simply replacing the batteries wouldn't fix.