Pagoda SL Group
W113 Pagoda SL Group => Electrical and Instruments => Topic started by: racefaith on April 09, 2016, 01:20:01
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Hello.
Car recently out of long mostly cosmetic resto. Car previously sat for about 5 years whilst other projects took prominence.
After starting up and driving for first time in awhile, car stopped cold. No gas. Determined original rear electric fuel pump burned out.
Replaced with new fuel pump.
Car fired right up. Drove it around. Went to park, turn key off and car still running. Try a few times to drive, stop, park, turn key, nothing, car stil running.
Finally just disconnected battery lead.
Discussed with long time mechanic. He felt it was a bad ignition "switch"...that he had replaced many over years that had "burnt out."
(this part I am calling a switch sits inside dash, is a round, partly metal, partly plastic piece with 8 copper colored prongs - please correct me)
Ordered new replacement switch.
Spent 2 hours bloodying my knuckles as a removed the tach, center stack and then speedo. I detach this whole ignition column - from front bezel to back wire coupling.
Installed new "switch" and reassembled. Before I start putting gauges back, I hold my breath and reattach battery. I turn key to 1 & 2nd position and things come to life. (I do not start engine)
1st gremlin: I turn key off and remove but hear the rear electrical fuel pump still running. Turn key back and forth and it does not stop. I detach battery, pump stops running. I reattach battery, pump runs. Back and forth.
2nd gremlin: concerned Ive got the wrong replacement switch or have assembled incorrectly, I pull everything apart. I then reattach battery and again, the fuel pump begins to run!!! (so does clock)
I begin to check every wire I can see for a possible cross, short, tear, mice chew, anything that might cause a problem. I check fuses repeatedly. I cannot see anything obvious.
My mechanic is convinced their is a wire worn someplace or chewed that is exposing it to metal. If true, he suggests reading schematics for fuel power system, clipping and running new set of wires to ensure it is connected by a clean and uncorrupted wire. (my fear is that someone along the chain of ownership/care made some modification or installation of something electric which corrupted a wire set and I then during my dash area clean-up during resto, i pulled some random wire.)
From a very simple standpoint, I cannot understand how anything can be running or engaged without the ignition throw or even installed!
APprecaite all troubleshooting thoughts. Thanks in advance, Chris
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http://www.sl113.org/forums/index.php?topic=4794.msg29829#msg29829
Check this thread...
I have seen a pagoda unable to be shut off because of low brake fluid....
I am sure that others on this site that better understand the electrical gremlins of 113's can explain the phenomenon.
Norm
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There are a lot of components that have power both from the ignition circuit and the battery seperately. If a component is shorted internally, the power can backfeed to other components through the fuseblock. Start by pulling the fuses one at a time to see if you can isolate a peticular circuit. For instance if you remove the wiper fuse and the fuel pump stops, you have found the circuit with the issue. You can also unplug components themselves such as the alternator field connector, wiper motor, gauge cluster bulkhead connector, and as Norm said, the brake reservoir electrical connectors. etc.. The fact that you can kill the car by disconnecting the battery means the alternator does not have a field reference from the ignition switch so that part of the circuit is probably ok. If you still have the wiring diagram in the back of your owners manual, it can help you trace out the circuits. Make a copy of it so you can write on it. X out the components and circuits as you test them.
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Look for electrical tape on wires where it doesn't belong - old repairs done poorly are often a source of many problems. This is always a good place to start as well as pulling each fuse as explained by Tyler.
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One more thing to consider is why the old pump failed. Is this because of the electrical issue? Or did the failure of the old pump cause wires to overheat and melt/short together? Check the amperage of the fuel pump fuse. Make sure it wasnt replaced by an incorrect fuse at one point. It should have an 8 amp fuse. This could have caused the pump circuit wires to melt and short with wires from another circuit when the old pump went south.
Depending on the model/year (280 only) the only wire going to the rear of the car that has a constant power supply without the ignition is the trunk lamp. May be worth checking that length of harness.