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  #1  
Old 01-17-2008, 01:43 PM
BMG BMG is offline
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1994 E320 Wagon - Dash electrical short(s)- any suggestions

Problem

No dash illumination lights - rheostat does work and adjusts all the remaining knob and switch lights on dash. Fues appears ok.

Turn signal indicators on dash normal when running lights / headlights are NOT on. Lights flash correctly and relay clicks as expected.

When running lights (no headlights) or running and headlights are switched on, both turn indicators on dash illuminate partially as well as the high beams indicator. When I use a turn signal, both indicators flash and the relay does NOT click. I also noticed that the Tach needle drops 400 rpm every flash of the turn signal.

Turn off lights (running and headlights) and problem goes away.

I do get a trouble light indicator for lights breifly when lights turned on but it quickly goes out.

Two other items (probably unrelated); Fuel guage level does not work (low fuel light does work fortunately). Oil Pressure guage is maxed out once the key is turned on (probably bad wire in engine compartment - I see bare wires where it comes thru firewall - to be replaced this weekend).

Items Checked so far

Pulled dash unit and checked its onboard fuse - ok
bulbs for Illumination - replaced - no change
Fuses in engine compartment ok.


I cannot pull codes off this car yet. It would appear that one of the previous owners disabled the check engine light and the diagnostic unit in front of the battery. I have that on my list to troubleshoot this weekend as well


Any suggestions on the Dash short issue?


Thanks in advance.

Brian

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Old 01-18-2008, 12:36 AM
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Brian

Sounds like you need to invest in the 124 Maintenance Manual (2 CD set). It includes wiring schematics.

Bob
PS I'll bet on a bad ground, especially when considering the butcher job the po did to it.
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Old 01-18-2008, 12:57 AM
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Has your wiring harness been replaced? Lot's of posts on the subject
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Old 01-18-2008, 12:57 PM
BMG BMG is offline
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Thanks for the replies

Bob

Calling it a "butcher job" is too generous. I was amazed after rebuilding the main engine harness that it ran at all. I did check all the grounds in the dash area and saw no unusual items or wires hanging.

Since the engine harness itself was in poor shape, I am worried that the portion of the lighting harness in the engine compartment leading to the two front light units is in as bad condition as the rest of the wiring was.

I plan on tracing that this weekend if I get some time. I have schematics on the car so I am good there.

TheEngineer
Point well made. The "engine" portion of the harness so often talked about is replaced. As noted, I suspect the problem is in the engine compartment exposed potion of the lighting harness. In the same area, the PO installed 14/2 nomex to try and repair the auxilliary fans for the radiator. That wiring is getting repaired this weekend.

All this wiring is in the same area as the ABS unit and I am willing to bet that the wiring to the ABS unit has the same problem (trouble light is lit on dash). I rebuilt the ETA harness using the following DIY article as a guide. My surging idle is now gone and when I fix the CC lever on my steering wheel, I will see if CC is back as well.
http://v12uberalles.com/throttle_actuator_rewire.htm

grrrr.... the more I think about list of little things (and big) I am fixing, the more I dope slap myself for not doing any research on the web prior to the purchase. Either way - I do love the car.

I report back anything I find this weekend.

__________________
Brian G.

1994 E320 Wagon with many warts SOLD
1995 E320 Wagon with a beauty mark or two FOR SALE
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