So, I've been having a bunch of problems lately (all seemingly related). My car wouldn't start a month or so ago and my mechanic replaced the CPS (probably didn't need to) and the fuel pump relay. The car worked fine for a few weeks until it wouldn't start at my office in Trenton. A mechanic there (not my usual guy) replaced the two in tank fuel pumps and then the rear SAM unit.

When I get the car back from this guy the supercharger won't engage. I had to take it to MB to get the SAM coded, so while I was there I had them check out the supercharger issue. They say it's the air charge circulation pump (IC pump). I had changed mine when I got the car a year and about 30K ago to the Johnson. I know this sounds like the normal life of the pump, but I just can't get over the fact that it supposedly died the EXACT same time as the pumps/SAM. The supercharger won't engage at all. It's not like last time when the supercharger would heat up and then cut out. It's just off.

Has anyone had their Johnson's die? If so, was it a gradual or immediate death? Could the SAM going have killed the pump?

Without the supercharger this car is easily the slowest car I've ever driven. As soon as it's gets out of second it's like I'm not even hitting the gas. It's killing me. Also, BTW the stealership wanted too charge me $681 to replace the pump. I had a hard time not laughing in their faces. I ordered a new one for 145.00. Hopefully it comes soon.

they do die, but they should last longer. maybe you have a bad fuse for the pump? IIRC, some guys had that happen.

one more vote for bad fuse. my CM30's been on the car for 3-4 yrs now no issues.

That was the first thing I thought. I checked them all this past Friday, but I'll check them again in the morning. I'm going off of the fuse charts from STAR so it's kind of confusing because it has all the fuses for all of the engines and stuff. It looks like the correct fuses are:

fuse 5 in rear SAM (20 amp)
fuse 51 in left engine compartment (7.5 amp)
and maybe fuse 36 interior drivers side (15 amps) though I pretty sure this one isn't for us.

If it helps any, the STAR readout says Code: P2074-004 Text: M44 (charge air cooler circulation pump) : short circuit to ground (P1999) Status: Current and stored

Just finished checking the fuses. They all look fine. I changed two of them just to be sure. I was really hoping that was the problem. Now I'm off to my really slow boring drive to work.

The air circulation pump is the smog pump above the passenger head light. The air circulation relay is known to go bad and keep the pump on until it burns out rather then shut off after 30 seconds. Its not the intercooler pump. Even with a bad intercooler pump, you would have 2 or 3 good runs before the sc would disengage.

That's what I was thinking. It's the "charge air cooler circulation pump". I mistakenly said air circulation pump and the MB tech corrected me. To make sure he was talking about the IC pump, I asked him, "you mean the Bosch unit located on the passenger side behind the splash guard in the wheel well?" He said yes. I really don't have any faith in his "yes" though. But since charge air cooler in another name for the intercooler, I didn't question him again.

Did you try listening for it? Usually you can hear it when you turn on the car.

Yeah, I've been trying to hear it, when I turn the car on and off. I need to get out and open the hood though, because I think I may be hearing the fan that kicks on automatically.

What did you end up doing to solve that " p2074 short to ground" ? it's the Intercooler Pump indeed as its name is M44. I have the same problem, not sure where to look for that short. If i clear the codes and restart i'll get the supercharger to kick in for the first 5 secondes, then it'll throw the code and it'll cut the supercharger.