So I am going to buy the garagistic motometer gears to fix my odometer and I noticed my speedometer and MPG meter coincidentally stopped working. My tac has also been buggy as I would have to hit it a little to get it to function. The speedometer and MPG don’t work at all though. What would cause this to happen? And what could be the issue with my tachometer? Would it just be better to swap the whole cluster with another 325e one? My current cluster was swapped by the way as it says redline is like 7 so that’s why i was thinking about just getting a new one.
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I've never had to "hit" the guages on either of my e30's to get them to work. They worked as long as there was power.
The only time my tach and MPG guage died, was because the Si batteries died (batteries dated late 1989, replaced in 2017 or so).
Since then, it's been working perfectlyIf it's got tits or tires, it's gonna cost ya! -
From what I garner, you’re running either a Frankenstein cluster or one pulled straight out of a 325i. The 325e cluster should show the redline at around 4700 RPM. Not sure what else has been done to your car, but it sounds your engine has been modified to rev higher or has been swapped hence the higher redline tachometer. If the engine is stock, then whoever swapped the cluster had no idea what they were doing.
Your speedometer not working could be caused by a few things:
1. Bad speed sensor on back of diff
2. Broken wiring between speed sensor and cluster (unlikely)
3. bad cluster circuit board
As for the tachometer, if you have a later-production Motometer tach (which I think you do), your issue is caused by either bad SI board batteries or a fault in the board itself. If your have the earlier-production VDO tach, then the issue is either caused by a wiring issue between the ECU and tach or a bad circuit board; the early-production tachs have their own circuitry on the gauge itself while the later-production tachs are just stepper motors that are controlled by the SI board.
My recommendation is that if you have a stock M20B27, find a good working VDO cluster, swap your speedometer into that, delete the SI board and jump pins 3 and 6 to ground your temp gauge. This way you get fully functional gauges and don’t have to worry about the SI board causing your tach to stop working 20 years down the road.1986 325e Schwarz (sold)
1989 325iX Alpineweiß (daily)
Greed is Good
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Sounds like you've got the wrong tach and/or tach chip installed for your car. I've got a 5k redline tach you can have for free but I don't have the chip for it. Take the old chip and tach out of your old cluster and swap it to your new cluster. Chip can be found at the front right of the face of your cluster."It wouldn't be there if it wasn't..." - Milton Berle
1988 325iS - M20Comment
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Yeah it’s definitely the wrong tach. It’s one of the later model motometers. My motor is stroked out with a 2.5 head so I think I’ll just try and swap in new so batteries if they’re pretty cheap until I get the 325e cluster. Thank you guys for the responses. The speedometer and MPG did work perfectly before going out so I think it’s just the batteries but the tach needing to be knocked on a couple times might just be it needing a replacement. Either way i only need the speedometer at the moment so it’s not a big deal.Comment
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Would that tach just slide right in without any type of retrofitting? I don’t really want to buy a whole new tach so if I can do that that’d be awesomeOriginally posted by E30Bastard View PostComment
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It swaps right in. Super easy, just be careful. Sent from my Pixel 2 XL using Tapatalk"It wouldn't be there if it wasn't..." - Milton Berle
1988 325iS - M20Comment
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if that's so that would be very cool of you. I don't feel like swapping clusters cause that would be like 60 bucks for a 325e one that has broken parts.Originally posted by E30Bastard View PostComment
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