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He guys and gals. I tried the search and didn't come up with anything so I'm asking the brain-trust here.
My 92 300D suddenly stopped talking to me yesterday on the way home. The instrument panel went to sleep. The speedo (and odo) still work as does the clock, but everything else is dead, needles at rest.
The speedo and odo are mechanical obviously (at least it is to me now) and the clock is a direct to battery connection. I don't have a schematic, besides a ground, is there anything else I should be looking for this weekend?

I appreciate the help, as always. I'm just trying to keep the old girl rattling down the road (296K as of yesterday).
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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Starting with the simple stuff first, make sure you battery terminals are clean and tight.

If your battery (should be a group49 sizewise) is more than 3-5 years old, replace with a new one and retest.

I have a suspicion that maybe there is a electrical issue and the battery drained itself.

Once you get the engine running, measure the voltage output at the cigarette lighter. Should be around 13.5V.
 

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Discussion Starter #3
Starting with the simple stuff first, make sure you battery terminals are clean and tight.

If your battery (should be a group49 sizewise) is more than 3-5 years old, replace with a new one and retest.

I have a suspicion that maybe there is a electrical issue and the battery drained itself.

Once you get the engine running, measure the voltage output at the cigarette lighter. Should be around 13.5V.
Sorry, I should have been clearer. The car runs great, started up three times today great. The battery is perfect (9 months old). It appears that the IP lost a connection, either supply or ground. But, knowing what I do about these W124's I assume there is some magic box somewhere that's gonna cost some coin haha.
Yeah, other than the gauges (except the speedo and clock) not working there are no other electrical symptoms that I've found.
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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OK, thanks for the clarification. That does help..

2 things to do next:

1) Replace every fuse in the fusebox with the updated copper core type. Less than $5 gets you a whole kit.

2) Remove the instrument cluster (carefully) and make sure that every connector going into the back of the cluster, especiallly the big round one towards the driver door) is connected properly and solidly. There is also a fuse on the back of the cluster, but this fuse is a dealer only item.

Additionallly, if not done already, replace the OVP relay with a new genuine MB or KAE(hler) OVP relay.

The injection pump is a fully mechanical device and has no direct connection to the instrument cluster. Your issue is strictly electrical.
 

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1988 300CE
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OK, thanks for the clarification. That does help..

2 things to do next:

1) Replace every fuse in the fusebox with the updated copper core type. Less than $5 gets you a whole kit.

2) Remove the instrument cluster (carefully) and make sure that every connector going into the back of the cluster, especiallly the big round one towards the driver door) is connected properly and solidly. There is also a fuse on the back of the cluster, but this fuse is a dealer only item.

Additionallly, if not done already, replace the OVP relay with a new genuine MB or KAE(hler) OVP relay.

The injection pump is a fully mechanical device and has no direct connection to the instrument cluster. Your issue is strictly electrical.
X 2
 

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Discussion Starter #6
OK, thanks for the clarification. That does help..

2 things to do next:

1) Replace every fuse in the fusebox with the updated copper core type. Less than $5 gets you a whole kit.

2) Remove the instrument cluster (carefully) and make sure that every connector going into the back of the cluster, especiallly the big round one towards the driver door) is connected properly and solidly. There is also a fuse on the back of the cluster, but this fuse is a dealer only item.

Additionallly, if not done already, replace the OVP relay with a new genuine MB or KAE(hler) OVP relay.

The injection pump is a fully mechanical device and has no direct connection to the instrument cluster. Your issue is strictly electrical.
Thanks sbaert, it's electrical for sure I just didn't know where to start so I appreciate being pointed in the right direction. This OVP relay, is that over-voltage protection? Where is this baby?
So, this weekend I'll replace the fuses, remove the IP and check the connections. I'll order the I'll check the fuse on the IP for continuity as well.
I'll let you know what I find.

Who knows what I'll find back there haha. About a year ago I was driving and hit a bump and felt something hit my foot. I stopped the car and found a very nice looking, and well used bong all wrapped in felt. Maybe I'll find a stash of cash back there?
 

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Yes the OVP is over-voltage protection, It is located behind a plastic housing behind the battery.
If their is a single fuse in there then it definitely needs replacing no matter what. The updated OVP has the 2 fuse.

and was the car owned by a drug dealer? A stash of cash would be nice :thumbsup:
 

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'95 E300 DIESEL, '91 600SEL, '92 600SEL
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DrBoost,

To minimize confusion, IP in the diesel world, means injection pump.

I'm thinking you are using the term IP to refer to the instrument panel.
 

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Discussion Starter #9
Yes the OVP is over-voltage protection, It is located behind a plastic housing behind the battery.
If their is a single fuse in there then it definitely needs replacing no matter what. The updated OVP has the 2 fuse.

and was the car owned by a drug dealer? A stash of cash would be nice :thumbsup:
Thanks for the info, I'll take a look-see at it this weekend.
 

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Discussion Starter #10
DrBoost,

To minimize confusion, IP in the diesel world, means injection pump.

I'm thinking you are using the term IP to refer to the instrument panel.
Ahh, now your response makes perfect sense. In the non-diesel world IP means instrument panel haha.

Well again sbaert, I owe you a beer. I decided to see if there were any other electrical issues I could associate with the dead instrument panel and I found that I had NO BRAKE LIGHTS!! So I pulled the fuse cover off again and found a bad fuse. It looked just fine (I looked at them this morning, but it was in the dawn light) but was cracked. So, I'm assuming it actually fatigued and cracked since there wasn't a soft, melted line but a clean, jagged break. I suppose that's why you said I should replace them with the other fuses huh?

I don't come here too often since I'm admittedly not a benz enthusiast but when I do, I sure to appreciate your help folks. And BTW, I do check every now and then to try to help others to keep the karma going around.
 

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The fuse issue is know in MB since W123 era. The fuse box have brass connectors, while standard US fuses have aluminum cores.
Copper/brass in contact with aluminum cost electrocorossion (just like galvanized pipes with copper pipes in some homes) and corrosion is resistor.
Get all copper fuses and you save yourself lot of pulled hairs.
 

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Discussion Starter #12
The fuse issue is know in MB since W123 era. The fuse box have brass connectors, while standard US fuses have aluminum cores.
Copper/brass in contact with aluminum cost electrocorossion (just like galvanized pipes with copper pipes in some homes) and corrosion is resistor.
Get all copper fuses and you save yourself lot of pulled hairs.

Ahh, ok. I thought it was just the aluminum getting brittle with age but the corrosion does make sense. I'll order a set of fuses this weekend.

I don't frequent many forums, but this one is right up there with Grassrootsmotorsports for a helpful, mature group of members. Thanks.
 
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