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BMW E30 3 Series 1984-1991 (318i/s, 325/e/i/is/ix, M3, conv) Tachometer not working


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Last Post: Mar 23, 2014 11:53 PM Last Post By: robert1858
flyboy

Posts: 14
Registered: 12/09/03
Tachometer not working
Posted: Sep 9, 2003 11:26 AM
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I just replaced the printed circuit board on my 1987 325ic. After I replaced it all of the gauges and lights except the tach are working correctly. I checked all of the fuses, they look good, check the connections, ditto.

Also the On Board Computer stop working as well. Don't know if it is related or just a dumb coincidence.

Here is the twist, the reason the board was replaced, the old one shorted out and caused smoke billow out from under the dash. When I removed it is was slightly melted, but no visible damage to anything else.

Could this have killed the Tach and Computer. If so how do I test them? Before I shut the car down the tach, fuel gauge and temp gauge danced around a little.

Thanks,
Anthony
Ronwigg

Posts: 5
Registered: 12/09/03
Re: Tachometer not working
Posted: Sep 17, 2003 7:19 PM   in response to: flyboy in response to: flyboy
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Check the connectors on the back of the gauge panel. I think that the power for the on board computer goes thru number 3, but if you wiggle them around with the engine running you may see the tach jump and or the OBC come on.
alpina

Posts: 1
Registered: 08/05/04
Re: Tachometer not working
Posted: Aug 5, 2004 11:30 AM   in response to: flyboy in response to: flyboy
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Good day
I was just reading the problem you had with your e30 with the tach and fuel econemy gauges not working also your on board computer i know this was a over a year a go, how ever i am having a same problem, the tach and fuel economy gauge and the on board computer are not working they came on for the first time in a well and they stopped working, if you have a suggestion it would be great
Charlie

Posts: 4,776
Registered: 12/09/03
Re: Tachometer not working
Posted: Aug 5, 2004 1:05 PM   in response to: alpina in response to: alpina
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The SI (Service Indicator) board inside the cluster itself. There are batteries AA NiCads on the board that go bad. Check with dealer for a replacement baord.
jsf252

Posts: 11
Registered: 08/09/04
Re: Tachometer not working
Posted: Aug 9, 2004 8:10 PM   in response to: Charlie in response to: Charlie
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I'm having the EXACT same problem with my '87 325ic. My Tach, temp, and fuel gauges stopped working. My A/C-heater blower, power mirrors, rear defroster doesn't work either.
I've done everything I know to do, and am having no luck. I've read some of these posts which sound just like my problems, but I'm not having any luck.

I've pulled the Cluster out, replaced the SI batteries (soldered) and nothing changed. I'm going to try the cluster while it's out, to see if there are any loose connections. But that still doesn't answer why my fan, rear defrost, and mirrors dont work.

I'm stumped, I'll try anything. One more thing, There is a small box outside/attached to the fusebox. it's about the size of a business card, and about an inch tall. There are 2 fuses inside, and I noticed my car is missing one. what are these fuses for?

Thank You in advance,
Josh F.

Charlie

Posts: 4,776
Registered: 12/09/03
Re: Tachometer not working
Posted: Aug 10, 2004 8:40 AM   in response to: jsf252 in response to: jsf252
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Mant times the batteries don't work. Need to complete SI baord. As far as the other electrical gremlins, do you have the complete wiring schematics for your vehicle? This is what you'll need to start the diagnosis process. www.centrallettershop.com sells the wiring on CD rom.
jsf252

Posts: 11
Registered: 08/09/04
Re: Tachometer not working
Posted: Aug 16, 2004 3:44 PM   in response to: Charlie in response to: Charlie
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Charlie,

Like I wrote in another thread, The reverse light wiring, coming from the transmission, seems to be the problem. (JayKool) had the same problem, and fixed it the same way.
I know none of the people who previously had this problem, replied with a solution, so I was going to let everyone know how to fix it.
Charlie

Posts: 4,776
Registered: 12/09/03
Re: Tachometer not working
Posted: Aug 16, 2004 4:21 PM   in response to: jsf252 in response to: jsf252
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The reverse light wiring caused a no tach problem? that sounds strange. I'd like to know more if you have the time to write it.
jsf252

Posts: 11
Registered: 08/09/04
Re: Tachometer not working
Posted: Aug 16, 2004 4:52 PM   in response to: Charlie in response to: Charlie
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Yep,
If you look on the "Fuses description" link on the BMW E30 Network,(http://www.bmwe30.net/cgibin/datacgi/database.cgifile=articles&report=view&ID=00046&Section=02) you'll see that #10 fuse is responsible for many things, Including the Tachometer/Fuel economy gauge. I think I said in a previous thread that I had a problem with the Back-up lights before. About a year ago, I blew a fuse, and some things in there interior stopped working. I check all over the car, and I read a thread about the reverse light wiring could be a problem. I jacked the car up, looked around the tranny, and sure enough there was 2 wires hanging down, and they had come in contact with the driveshaft. They had obviously been like this for a while, as the casing on the wires was rubbed off. When they came in contact with the driveshaft they grounded, and blew a fuse (dont think it was #10.
A couple weeks ago I had the tach, fuel, and temp gauges stop working, along with the electric mirrors, heater fan, and rear defrost. I knew I had blown a fuse, so I checked them all. I found nothing blown (at the time). So I started checking other things. I noticed that if I turned the fan on, then started the engine, the fan would blow until I released the key (disengaged the starter). I unplugged the starter, and everything worked fine, even when the key was in the "on" position, and not "start". After this I was stumped (again) and I gave it a break. I started fresh on the car Sunday afternoon. I knew some other guys had missed fuses before, and thought that I should re-check them. I went back through them, and examined them REALLY close. I noticed #10 was blown, but you had to look really hard to see it. So I replaced this fuse, tried the ignition again (starter was plugged up), And it immediately blew the fuse (#10). So I decided to check the reverse light wiring one more time. There weren't any bare spot underneath the car, but inside where the wires run through the rubber shift boot. There were two small holes 1/16" x 1/16" square. They were grounding on the metal around the rubber shift boot. My shift boot is torn, and lets the wires touch the metal; I'm getting a new one. So anyhow I Isolated these wires, taped the worn spots, and replaced the #10 fuse. Turned the key, the tach, temp, and all the other non-functioning electronics came to life!
That's about as detailed as I can get.
Josh F.
jsf252

Posts: 11
Registered: 08/09/04
Re: Tachometer not working
Posted: Aug 16, 2004 4:59 PM   in response to: jsf252 in response to: jsf252
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Also, I wonder if it makes a difference in the spots it was grounding out. Before it was grounding out on the driveshaft, that caused a few problems. But now that it's grounding out on the transmission tunnel (hole that shifter goes through) it's causing different problems. I guess that's why I didnt' think that it was the reverse lights to begin with.

I do have a question though, on the outside of the fuse box, there is another small box attached. It is about the size of a business card, and 1" tall. It houses 2 "old-style" fuses. One of them is missing on my car (fuse toward rear of car). Do you know what these control??? I checked my other E30's and they dont have them ('84 325e, and '83 323i).

Thanks Charlie,
Josh F.

Message was edited by: jsf252

Charlie

Posts: 4,776
Registered: 12/09/03
Re: Tachometer not working
Posted: Aug 16, 2004 5:24 PM   in response to: jsf252 in response to: jsf252
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Thanks. I did read the write up right after I made the post.
Charlie

Posts: 4,776
Registered: 12/09/03
Re: Tachometer not working
Posted: Aug 17, 2004 7:53 AM   in response to: jsf252 in response to: jsf252
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Hi Josh,

These are Auxiliary fuses for add-ons... Not active until you add-on something. Then you can fuse them to whatever rating you need. If there is one fuse installed, maybe something was added on (?) after the fact, but only you can't find that out.
jsf252

Posts: 11
Registered: 08/09/04
Re: Tachometer not working
Posted: Aug 17, 2004 9:43 AM   in response to: Charlie in response to: Charlie
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Charlie,

Thanks for the help, I've been searching everywhere to try and find what these fuses are for. None of the "experienced" E30 guys knew, or wanted to tell me.

It's a shame, but the previous owner of this car did a lot of splicing and rewiring. He has opened the wiring harness in several spots (cut open the factory wrapping), and it looks like a bird's nest in spots, not to mention the hoard of barrel splices (underneath the dash mostly). I hate working on something that someone else has already messed with.
I've pondered getting a new wiring harness, just to make sure everything is correctly wired. Do you know what a wiring harness usually costs? Where to get one?
Your help is much appreciated, take care,
Josh F.
Charlie

Posts: 4,776
Registered: 12/09/03
Re: Tachometer not working
Posted: Aug 17, 2004 11:28 AM   in response to: jsf252 in response to: jsf252
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A good salvage yard could get you a complete harness in one peice. Someone like Vines in Alababma or Active in Memphis. Check the Roundel (the BMW Car Club Magazine). I would guess like 200-300 would get you one??? Good luck.
littlebear

Posts: 1
Registered: 11/02/04
Re: Tachometer not working
Posted: Nov 2, 2004 2:08 PM   in response to: jsf252 in response to: jsf252
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Fuse #10 is probably blown. There is a pair of wires that passes thru the gearshift hole and rubs against metal until it shorts. Bet that's it, that was the problem on two of my e30's
cam1997

Posts: 1
Registered: 03/02/14
Re: Tachometer not working
Posted: Mar 2, 2014 8:44 PM   in response to: flyboy in response to: flyboy
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i have a 1990 e30 325i i just bought it, the tachometer works fine in all gears but when you go into reverse it stops, also the oil temperature gauge has stopped working, can someone give me tips on fixing this issue? thanks
robert1858

Posts: 2
Registered: 03/23/14
Re: Tachometer not working
Posted: Mar 23, 2014 11:51 PM   in response to: flyboy in response to: flyboy
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Thanks alot to everyone who posts information towards problem solving ....my 1991 318 I e 30 has a Rachel malfunction. 300.000 miles, first the MPG gauge stuck for a few miles, then started working. Right after that the tach malfunctioned. Reads 7-8000 rpms when it should bee at 4000 then when engine earns up it will read correctly.
robert1858

Posts: 2
Registered: 03/23/14
Re: Tachometer not working
Posted: Mar 23, 2014 11:53 PM   in response to: flyboy in response to: flyboy
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Thanks alot to everyone who posts information towards problem solving ....my 1991 318 I e 30 has a Rachel malfunction. 300.000 miles, first the MPG gauge stuck for a few miles, then started working. Right after that the tach malfunctioned. Reads 7-8000 rpms when it should bee at 4000 then when engine earns up it will read correctly.

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