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#1
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temp guage and rpm guage inoperative after wiring harness replacement
Hi -- Just installed new wiring harness while fixing leaking fuel lines, etc.
RPM gauge worked for 2-3 minutes and cut out. Temp gauge not working at all. Both were working fine before work but I was having other intermittent electrical issues over last year. Should I check the OVP relay and replace if necessary. Should I check temp sensor/sender? Any other suggestions? Where is the sensor that sends to the gauge on the 1995 OM606? Thanks!
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-- Chris '95 E300, 216k miles, Silver Surfer '05 E320 CDI, 138k miles '07 S550 4matic, 69k miles Gone but not forgotten: '76 300D, 350k miles?, SOLD in 1995 '75 240D, 300k miles, SOLD in 1991 |
#2
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Does the a/c compressor work? If so, the OVP relay is good. The Klima relay requires a signal from the tach before it will allow the compressor to engage. The tach and coolant temp gauge really aren't related; hard to see a single problem causing both. Check all the fuses -- don't just look, remove them and make sure each is not cracked or corroded. Remember the fuse in the OVP relay. Check the connection at the temperature sender, make sure the connector got plugged back onto the sender when the wiring harness work was done. Ditto the RPM sensor at the flywheel (below/near the starter motor).
Jeremy
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"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 |
#3
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Hi Jeremy -- Thanks. Will check these out tomorrow. I also removed the combination heater control valve/ aux pump to rebuild as I have a small leak there. Unplugging the sensors to the heater valve and aux pump should not have killed the rpm or temp sensor.
The coolant hoses were capped during the project. I did not touch the rpm sensor but did move the cable while doing the wiring harness. -- Chris
__________________
-- Chris '95 E300, 216k miles, Silver Surfer '05 E320 CDI, 138k miles '07 S550 4matic, 69k miles Gone but not forgotten: '76 300D, 350k miles?, SOLD in 1995 '75 240D, 300k miles, SOLD in 1991 |
#4
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Leak
Let me know how the leak repair goes. I've replaced that pump/monovalve assembly twice this year due to leaks. The new ones last about a month and then crack and start to leak for no reason I can determine. I'm currently working with MBNA to figure out what's going wrong.
Note that in our specific model ('95 E300) the monovalve switches coolant flow from the head back to the thermostat housing. The coolant flows through the heater or bypasses it, depending on what the Climate Control Unit (CCU) tells the monovalve. With the hoses capped there is no flow from the back of the head. I hope that won't hurt the engine. I believe the 300D-2.5 Turbo engine also uses that pump/valve (001-830-40-84). The pictures show the second replacement (replaced on warranty by MBNA) Jeremy
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"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 Last edited by Jeremy5848; 04-15-2013 at 11:48 AM. |
#5
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I replaced my assembly with another one from Germany that was used. It cracked later as well. I am now trying to rebuild but in the mean time have capped the coolant hoses. Should I loop the circuit?
__________________
-- Chris '95 E300, 216k miles, Silver Surfer '05 E320 CDI, 138k miles '07 S550 4matic, 69k miles Gone but not forgotten: '76 300D, 350k miles?, SOLD in 1995 '75 240D, 300k miles, SOLD in 1991 |
#6
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Loop
Quote:
You may have to pull the battery and battery pan to see which of the three hoses runs behind the engine. Two of the hoses go into the firewall and lead to the heater core (the same heater core is used in cars that have dual controls, hence two outlets). The third hose connects to a pipe that runs behind the engine and connects to the head. On the forward end of the valve/pump are two hoses. The little one can be left capped -- it feeds the windshield washer bottle heater. The larger hose is the return-to-thermostat hose. Connect it to the one that runs behind the engine. That will allow coolant to flow from the head back to the thermostat and on to the radiator. May not be necessary but who knows. If you figure out a repair please share. MBUSA has asked me to have my dealer contact an MB rep to come see the leak with the part still in my car. Maybe there was a defect in the manufacturing process. Jeremy
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"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 Last edited by Jeremy5848; 04-15-2013 at 11:32 AM. Reason: Additional text |
#7
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Checked compressor and it indeed does not cycle on. So I have no rpm, no temp gauge and no tachometer. I have ordered a new OVP and will see if that helps.
RE: combo mono valve/pump assembly, I will interested to hear what the zone rep. has to say about it. I have thought the design was poor....the added hose connection below the mono valve looks like it is made of a different material then the rest of the assembly. The two I have have also cracked in that upper area. It may be weak material combined with the stress of the hose pulling it down. -- Chris
__________________
-- Chris '95 E300, 216k miles, Silver Surfer '05 E320 CDI, 138k miles '07 S550 4matic, 69k miles Gone but not forgotten: '76 300D, 350k miles?, SOLD in 1995 '75 240D, 300k miles, SOLD in 1991 |
#8
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Quote:
If there is no RPM signal, the AC compressor will not engage. While this could be related to the OVP, it's highly suspicious that it died right after replacing the harness. Double check the connections, and the flywheel/crank sensor itself is also suspect. The two issues should not be related. Question: Did you install a brand new harness, or a good used harness? |
#9
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I used a harness rebuilt by a firm in Utah: Rush Power Systems. The harness came back better then stock (over engineered). It was also checked and QCed several times before being shipped back to me.
The glow plug light on the dash now comes on and stays lit for longer then pre-wire harness replacement.
__________________
-- Chris '95 E300, 216k miles, Silver Surfer '05 E320 CDI, 138k miles '07 S550 4matic, 69k miles Gone but not forgotten: '76 300D, 350k miles?, SOLD in 1995 '75 240D, 300k miles, SOLD in 1991 |
#10
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Hmmm. That makes me wonder if the two pins for the sender got reversed. If so, that would explain both the long glow time, and the dead temp gauge (assuming it remains down at 40C all the time).
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#11
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Good news
Quote:
Jeremy
__________________
"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 |
#12
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Any trick to replacing the OVP in this model? Should I disconnect the battery?
__________________
-- Chris '95 E300, 216k miles, Silver Surfer '05 E320 CDI, 138k miles '07 S550 4matic, 69k miles Gone but not forgotten: '76 300D, 350k miles?, SOLD in 1995 '75 240D, 300k miles, SOLD in 1991 |
#13
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OVP
Quote:
Jeremy
__________________
"Buster" in the '95 Our all-Diesel family 1996 E300D (W210) . .338,000 miles Wife's car 2005 E320 CDI . . 113,000 miles My car Santa Rosa population 176,762 (2022) Total. . . . . . . . . . . . 627,762 "Oh lord won't you buy me a Mercedes Benz." -- Janis Joplin, October 1, 1970 |
#14
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Problem solved!
Thanks for the help! The new OVP solved the problem with the rpm gauge/compressor. I had the temp. gauge sensor reversed with the one that plugs into the back of the fuel pump.
The vehicle runs a lot better. My next project will be to change the belt tensioning system to quiet things down while the vehicle is idling.
__________________
-- Chris '95 E300, 216k miles, Silver Surfer '05 E320 CDI, 138k miles '07 S550 4matic, 69k miles Gone but not forgotten: '76 300D, 350k miles?, SOLD in 1995 '75 240D, 300k miles, SOLD in 1991 |
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