Tach and Speedo stopped working after battery swap?

[Gusfazekas]

I have a '95 SL500, my battery died and I jumped the battery to start the car. Everything was worked fine as I drove to AutoZone, that is, until I restarted the car after replacement of the battery. I watched as the AutoZone tech struggled to move the positive wires aside to remove and replace the battery, it was a struggle. After the car started, both Tach and Speedo quit working on start-up.

What could have happened? Might it be a fuse or possibly a positive wire issue at the battery? Is there a fuse for both speedo and the tach?

Thanks Steve

[Gusfazekas]

Here's some updated info. I don't know what's wrong with my cluster or what caused the speedo and the tach to quit working, but I'm amazed that out of 99 guys that have viewed this post and about another 100 or so that have read my question posted in the Tech Section, that only Tecqboy and Doc had any thoughts on the subject. With Tecqboys post and some "lucky" phone calls around the country, I now have a notion that a part in the cluster has failed.

Let you know what the outcome is, just in case this might happen to you.

Lets just say I'm a little frustrated by the lack of response or interest in sharing or helping a fellow Benz devotee.

Steve

[mach4]

Originally Posted by Gusfazekas

Here's some updated info. I don't know what's wrong with my cluster or what caused the speedo and the tach to quit working, but I'm amazed that out of 99 guys that have viewed this post and about another 100 or so that have read my question posted in the Tech Section, that only Tecqboy and Doc had any thoughts on the subject. With Tecqboys post and some "lucky" phone calls around the country, I now have a notion that a part in the cluster has failed.

Let you know what the outcome is, just in case this might happen to you.

Lets just say I'm a little frustrated by the lack of response or interest in sharing or helping a fellow Benz devotee.

Copping an attitude is no way to get your fellow forum members to help out. It's probably more likely that there was no logical explanation for what you experienced and therefore no meaningful response was possible. It's highly likely that there are not that many SL500 owners on the forum meaning that of the 100 readers of the post, maybe 20 have a frame of reference.

Oh, and by the way, it just happens sometimes, it's not just you....

[Gusfazekas]

Mach4, I hear you and I appreciate the links showing others without responses as well. Without trying to be offensive, I was frustrated because there are many followers of this site who are technically capable of offering up some suggestions. I view the Forum as a place to share information with people of varying levels of expertise. Maybe I'm wrong. I thought I'd get a conversation started re: what it means to be a member and contributor. The SL500 isn't so different from other Benz models that there are no common faults. I will post when I have a resolution to my problem, and hope to provide help to any one else who asks.

Thanks for your thoughts, Steve

[DAVECAD2.0]

Originally Posted by Gusfazekas

Mach4, I hear you and I appreciate the links showing others without responses as well. Without trying to be offensive, I was frustrated because there are many followers of this site who are technically capable of offering up some suggestions. I view the Forum as a place to share information with people of varying levels of expertise. Maybe I'm wrong. I thought I'd get a conversation started re: what it means to be a member and contributor. The SL500 isn't so different from other Benz models that there are no common faults. I will post when I have a resolution to my problem, and hope to provide help to any one else who asks.

Thanks for your thoughts, Steve

As an aside I posted about my Tach on a '91 420SEL not working and also got no response. It's no big deal 'cause I've never quite figured out of what use a Tach is on a slush box anyway. But, still it's there and anally I would like it to work.
Still broke.

[tecqboy]

I read all the posts in the SL forum almost everyday. I usually check the tech help too. My only practical Mercedes experience is with the 1991 SL I own. But I've a good background in electronics and domestic vehicle repair. The problem with responding to some posts is that I can't judge the level of automotive skill the questioner has. I don't want to get them into more trouble than they can handle. Often the symptoms are poorly described. And often, I'm wrong. Sometimes it's obvious they should go to a dealer or pro shop for their problems. But I recognise that in many cases there are other guys here who are much more experienced than I am, so I don't respond to those questions. This forum has been a tremendous help to me in keeping my car in great condition while keeping my cost of ownership low. If I had to go to the dealer everytime there was a problem, I couldn't afford keep this old vehicle. So thanks to everyone here who share their experiences.

[mach4]

Originally Posted by Gusfazekas

I thought I'd get a conversation started re: what it means to be a member and contributor.

OK, I'll bite.

As I view these fora, the primary purpose is to seek help and assistance for DIY projects. That is by no means the only purpose, but it's a good place to start. So, as I've been hanging around, there are some basic presuppositions and values that drive things. The first is that the OP has done some preliminary search on the forum and has either come up empty or has located some similar issues and tried what was suggested without luck. Second, that the OP has attempted some initial troubleshooting activity and has ruled out certain items or has uncovered additional data that has led to a dead end.

So let's analyze the post that began this thread. It appears that the battery died and the OP went to the store to have a new battery put in. Most DIYers in this situation would get the new battery and, rather than trust some store guy, would install it themselves - to avoid the potential situation that the OP describes of "struggling" to install the battery. So there is a potential cause-and-effect relationship between the battery and the tach, but maybe not.

Without any troubleshooting whatever, the OP poses some questions

What could have happened?

Heck, anything could have happened. It would take a book to exhaust the possibilities.

Might it be a fuse or possibly a positive wire issue at the battery?

Ok, good observation. But if raises questions for the reader - "is the OP incapable of checking a fuse?" If so, the only logical response is to take it to the dealer, if not, what is the result of checking the fuses? Since there is no data on the status of the fuses, the next question that comes up is, "is the OP too lazy to check the fuses and report the results". Same for the second portion of the question about "positive wires at the battery". Has the OP looked at the wires? Do they look ok? Is there some question about one or more? Is the OP incapable of recognizing a broken wire...

Is there a fuse for both speedo and the tach?

This is actually a good question, as on some MB there is a OVP relay and fuse. But to be sure, one needs to look at the wiring diagram for the vehicle. The OP would be well advised to check the wiring diagram in order to know. A fair question to the forum might be where is the OVP? as these kinds of things can be very obscure.

It's my belief that one should never be critical without offering a solution. Let me take a crack at re-writing the post in such a way that I think would garner some replies.

-------------------------------

I have a '95 SL500, my battery died and I jumped the battery to start the car. I took the car to AutoZone, and had them install the battery. Normally, I'd pick up the battery and install it myself, but I thought I'd save a trip and have them do it - what could go wrong? Right?
I watched as the AutoZone tech struggled to move the positive wires aside to remove and replace the battery.

When I restarted the car after replacement of the battery, I noticed that both the Tach and Speedo quit working. I asked the tech about the problem and got no satisfactory answer.

What could have happened? My first inclination was that a wire got messed up but I checked everything in the battery area and everything looks good. I even pulled the battery and reinstalled it to make sure things were done right.

Then I thought "Might it be a fuse?" So I checked the fuse box and all the fuses are good. I even replaced the fuse for the cluster to eliminate corrosion as a possibility". Other items in the cluster are working fine, so I don't believe it could be power to the cluster, or a ground for that matter.

Then I wondered whether there a fuse for both speedo and the tach? I looked online for a wiring diagram and came up empty?

So I have two questions?

Can someone point me to a wiring diagram for the cluster?
Can you suggest other things to check at this point?

Never trust the techs at Autozone, WalMart or KMart to change a battery.

--------------------------------------

Now we've got something to work with.

[Gusfazekas]

Mach4 Thank You for your suggestions. I actually started this post on the Tech side of the forum before I posted an abridged version on the SL Forum. Look, I really like my SL but I live 50 miles from the nearest MBZ dealer and I haven't had much luck in my smaller town outside of Cleveland with indies who don't see this type of vehicle. So you can see that its not easy to get some direction to find the problems I've had. I like the forums (fora) but I've just found it frustrating because I know there are former/retired techs that have the knowledge base to help but don't reply or maybe start to help and than drop it without further comment. That's what I find frustrating. I don't know that I would ever buy another of this vintage because of all of the problems I've had but I'm not ready to ditch it yet if I can do the repairs myself.

By the way, Is there any OVP on a '95 SL? I have a subscription with AllData DIY and I have Mitchells and a CD for this car but the amount of information for the problem I have is seriously lacking. Heck, Weds., I asked if anyone could tell me how to remove the wires from the cluster without damaging the wires and had no response.

I'm off my soapbox and have taken my morning Xanax,

Thanks, Steve

[duxthe1]

Under the hood there is a cover near the firewall on the passenger side. The diagnostic port is in this cover. Under this cover there is a module box, you want to remove its cover as well. Inside there should be a module that has 4 red 10A fuses in its top. Check those fuses, likely one is blown.

FWIW, I usually look for posts with 0 replies to try to help out on tough problems, but rarely visit the SL sub-section..

[Gusfazekas]

Thanks Duxthe1, Per MBDocs suggestion last week, that was one of the first things I checked but they were all OK. Subsequent discussions with Hogweed and others including a cluster repair center in Tampa, I've discovered that vehicles that have their batteries drain and follow-up "jumping" and/or charging to start, can cause a part in the cluster to fail affecting tach and speedo. The Tampa facility says this is common on many Benzs stored there over the summer/fall and restarted/jumped in winter when the snowbirds return. I've jumped and started mine in the past without issue, but not this last time. I'll report back when my cluster is returned to me. I'm hoping the problem is the cluster and not something else I can't find.
By the way, I've decided to sell my SL because I bought a mint and cheap '03 Audi A4 conv't Saturday that I hope will be less problematic. My SL is now officially for sale.

Everything that can go wrong with my '95 has and all of the repairs have been made. There isn't much left to "fail" so this will be a bargain for someone looking for one.

Steve

[dkveuro]

''By the way, I've decided to sell my SL because I bought a mint and cheap '03 Audi A4 conv't Saturday that I hope will be less problematic. ...''

Well...good luck with that. I have been working on Audi for a good many years and to think it may be less problematic than the MB is a little doubtful.

Anyway...to address your cluster problem....allowing for the Auto-Zone indecent, I suspect you have damaged the cluster due to repeated battery contact/disconnect at the battery post during installation of said battery.

I suggest you send the cluster to Beckmann Tech and have them check it for you.
Go to the web site and send an email to Robert. I have always had great service from them.

PS...If your cluster is now working...what was the problem ?.... as inquiring minds would like to know.


.

[dkveuro]

Doh ! Didn't fully read your last post

....but I repeat, Beckmann Tech is IMHO the best place for MB electronic help.
So we await on the place you sent it for diagnosis.

.