'94 E420 cuts out over bumps

[PMPaniccia]

Joined a while ago and haven't gotten around to posting, my dad has a 1994 E420 that I bought from a friend.

It has (after coming out of winter storage) developed an interesting problem. When on the highway if you hit a bump the motor momentarily cuts out. At low speed in a parking lot he hit a bump and the motor entirely turned off. It restarted easily.

Sometimes when the motor cuts out the ABS light flashes.

I'm sort of at a loss. The original owner did the harness, and my friend had the ETA done. Probably not related but wanted to mention up front those two big items have already been done on this car.

Any insight is appreciated!

 

[vatc5637]

I'd check the simplest things first, battery cables, fuses/fusebox, then negative ground on lower(?) wiring harness. Good luck.

 

[gerryvz]

Check your battery connections in the trunk. Make sure all terminals are clean (brush off with a wire brush if needed) and TIGHT.


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[Klink]

What Terry and Gerry said just above. Also, pay extra attention to the small positive wires attached to the positive battery terminal, and the condition/tightness of the chassis connection at the other end of the negative battery cable. You are describing the classic symptom of looseness at major electrical connections, and those are most commonly found at or near the battery.

 

[PMPaniccia]

Thanks for the insight guys, I'll see what diagnosis dad can do over the phone, otherwise next time I am down there (need to roll a timing chain into this 300D 2.5 soon anyway) or next time he drives the 420 up here I will look over all of the connections.

Called him and told him what to look for, he's going to look today and call me back. I'll be curious to hear. I didn't realize there were some additional wires attached to the positive terminal. That's how my D-jet 3.5s are and I've seen people have cut-out issues when that extra wire is loose.

I like that theory, straightforward and easy to fix. Thus, it can't possibly be that! Stay tuned.

 

[samiam44]

Check the lower harness to see if the big lead to the alternator has good insulation and is not touching anything.

 

[PMPaniccia]

Found the issue when dad came to town for Brunch on Sunday.

Nut was missing, so the extra wire on the positive terminal was bouncing around and sparking. Got a new nut and cleaned up the terminal. No issues since.

 

[modzona]

So often the most basic and easiest thing that is the culprit

 

[gerryvz]

Absolutely as I thought. Lots of corrosion on there, too. Hope you brushed things off. Glad you found the issue.

Cheers,
Gerry

 

[Shah Kar]

check the air intake department also, if some scrws are loos, jumping the bump it takes air from where the gasget is and he engine turnes off momentantly

 

[PMPaniccia]

Absolutely as I thought. Lots of corrosion on there, too. Hope you brushed things off. Glad you found the issue.

Cheers,
Gerry

You nailed it, I try to post back to threads like this so others can learn from what happened. Often people don't come back after they resolve their issue.