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#1
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Where does the guage cluster get ground from?
I have a 85 300SD and I am wondering where the dash cluster gets ground. I posted a thread on here a few weeks ago about my fuel, oil pressure and temp all reading at there maximum reading. http://www.peachparts.com/shopforum/showthread.php?t=234545
Today I went to the local pick and pull and bought a complete guage cluster and the board that it attaches to. It is still doing the same thing. I know I have a short somewhere or possibly not getting enough ground. There are four metal tabs that attach to the dash where the cluster seats into it...i dont see how the cluster would be able to recieve ground from these tabs. I tried wiggling the cluster to see if it was a simple contact and still nothing. I have checked the fuses and they are all fine. What should I do next? -Stephen
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68 250s SOLD 78 300d non turbo SOLD 1980 240d manual SOLD 1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman 1977 300d non turbo SOLD 1985 300SD california car 1978 240D Manual |
#2
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Good question. I added a ground cable to the cluster on my '83 240D... I *think* that the ground comes through the wiring. I suspect on mine I've pulled a wire slightly out of the bundle that comes into the back of the cluster...
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Sadly Benz-less |
#3
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I mentioned in my other post that when i put ground to the metal backing of the cluster the guages work fine....i am not sure about that anymore because when i have ground to it and turn on the high beams the guages still go haywire.
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68 250s SOLD 78 300d non turbo SOLD 1980 240d manual SOLD 1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman 1977 300d non turbo SOLD 1985 300SD california car 1978 240D Manual |
#4
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When you pull the instrument cluster, there are several terminal ends screwed to the chassis behind it. Also, check the engine-to-chassis ground strap located near the starter.
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
#5
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I do not see any terminals or anything that would be able to ground the dash cluster except for the little clips that attach to the dash that hold in the cluster but even then they only touch the plastic.
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68 250s SOLD 78 300d non turbo SOLD 1980 240d manual SOLD 1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman 1977 300d non turbo SOLD 1985 300SD california car 1978 240D Manual |
#6
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Some of the electrical wires that run to the various connectors on the instrument cluster are attached to the grounding points. There isn't a "ground strap" if that is what you are thinking of.
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
#7
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Ground Wires
Mercedes Engineers are fixated on using Brown insulating for Ground wires.
I'd be willing to bet,that you can find a "Ground Point" behind the IC.
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'84 300SD sold 124.128 |
#8
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the only wires that attach to the cluster is a wire harness, sppedometer wires, clock and lights. I do not see how the cluster as a whole can get ground because the dash is insulated bu foam or plastic. Keep in mind that all of the guages worked before i took the cluster out, replaced the turn indicator light and put it back in.There is nothing in the dash or on the instrument cluster that would indicate it is recieving ground or any other type of electricity from terminals inside the dash. I own two SD and neither posess what you speak of. Are we talking about the same thing?
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68 250s SOLD 78 300d non turbo SOLD 1980 240d manual SOLD 1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman 1977 300d non turbo SOLD 1985 300SD california car 1978 240D Manual |
#9
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The ground will come through one of the wires to the plug you plug in. Add an extra ground wire with a connect/disconnect in the middle of it. You can attach it at a grounding point behind the cluster and to one of the screws that contact the metal plating on the back of the cluster itself.
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Jimmy L. '05 Acura TL 6MT 2001 ML430 My Spare Gone: '95 E300 188K "Batmobile" Texas Unfriendly Black '85 300TD 235K "The Wagon" Texas Friendly White '80 240D 154K "China" Scar engine installed '81 300TD 240K "Smash" '80 240D 230K "The Squash" '81 240D 293K"Scar" Rear ended harder than Elton John |
#10
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Quote:
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68 250s SOLD 78 300d non turbo SOLD 1980 240d manual SOLD 1981 300SD 360,000 miles I think she's doomed for a parts car but has a good engine SOLD the engine to spamman 1977 300d non turbo SOLD 1985 300SD california car 1978 240D Manual |
#11
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Quote:
mine also has an extra ground run from the rear of the dash to a screw on the cluster, you cant have too much ground. the designers had the luxery of new wire and good contacts at every juncture, you now have a 25 year old car, some adjustments need to be made unless you want to replace the entire harness and redo all of the connections. just make it with a faston in the middle so it is easy to unplug when servicing the cluster
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1982 300CD Turbo (Otis, "ups & downs") parts for sale 2003 TJ with Hemi (to go anywhere, quickly) sold 2001 Excursion Powerstroke (to go dependably) 1970 Mustang 428SCJ (to go fast) 1962 Corvette LS1 (to go in style) 2001 Schwinn Grape Krate 10spd (if all else fails) |
#12
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I don't know how I can explain this any better........
Each one of the connectors attached to the instrument cluster has a brown wire. One end is the connector the other end of the wire is where it attaches to ground. If you will pull the cluster and look! There are several of these brown wires attached, with screws, to a chassis rib behind the cluster. Those are instrument cluster grounds. So far you have not mentioned checking the engine-to-chassis ground or the battery-to-chassis ground. Since these are engine guages, the engine-chassis ground can be part of this problem. Check the ground of the headlights also. I'm sorry but I feel like I'm repeating myself.
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Sam 84 300SD 350K+ miles ( Blue Belle ) |
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