PeachParts Mercedes-Benz Forum - View Single Post - Secondary Air Pump

Syntax26 · #18 06-04-2008, 08:28 PM

Hi Arthur,

How are you doing? Hope all is good with you.

Well, unfortunately I have bad news and worse news to report.

I received the replacement relay today. I put it in, checked that I'd left no wires un-re-attached, and started the car. The pump clutch did not engage.

I cleaned the female sockets to the relay -still no pump clutch.

I then removed the relay - jumped the load relay sockets - the clutch did engage.

I tested voltage at the coil sockets - with the engine running - 4.5 volts!
(So my self-critical comments yesterday about having read 5v with the ignition on, engine off - I was wrong. I did get 5/4.5v the other night.)

So I suppose this means the coil is not getting energized (low voltage situation)...but I just spit this statement out -quite frankly, I'm not sure of anything at this point.

Anyway...upon the 3rd ignition cycle - CEL came on, and the same 2 codes returned (Pin 4 = Code 11 = Open circuit secondary air...& Pin 19 = Code 4 = air injection system faulty).

The above is the bad news. Here is the worse news - coming from my attempt to test drive the car AFTER the above.

For the few weeks I experienced the CEL and these codes - at least the only "performance" symptom was that the engine did not accelerate well from standing stop to mid-rpm's.

During the test drive the car went into what I believe to be limp home mode. I use the word "believe" because I had never experienced this on the car before...I've only read it here on the forum and in manuals.

The symptoms were:

1. The throttle pedal became unresponsive
2. The engine would not rev - it would choke
3. The situation cleared up by cycling the ignition (i.e. turn it off, turn it back on).

So...that is that. I'll put my thinking cap on and read some more to see if I come up with any ideas.

If you'd like to throw a thought my way...I'd appreciate it. Naturally, I don't want to impose upon you, so if you're busy, I understand.

Anyway, thanks for your help so far.

Take Care!

Jim