jknust

Hi all,

Having some strange problems.... looking for ideas or advice.

A few weeks ago, on a normal trip, the car decided in the middle of the trip it would not shift past 3rd gear. It was fine earlier... shifting through the range during the trip. When this happened it was in C mode, and pressing the mode button would not switch it to M or S - was stuck on C. I could hit the steering paddles, and 3 would show up on the dash, and I could go up to 4 or D, but it still did not shift. I did not hit the paddles to go down below 3rd, as I was worried about getting stuck in a lower gear. Once I came to a stop sign on this trip, and the car automatically downshifted to 2cnd gear, it then became "stuck" in 2cnd - same symptoms with the paddles and inability to change modes out of C. Once I got home, I shut off the car, restarted it, pressed the Mode button and they could be changed - drove around the neighborhood and up the street and everything was back to normal. I thought it was just a "hiccup" - no CEL or other symptoms. Past few weeks on various trips (several hundred miles, in town and highway) no other problems... so I really thought it was a fluke.

Today, though, I was in C mode pulling out of a parking lot under normal driving, and it was lingering in 1st (maybe up to about 3k - 3.5k) and did a harder than normal shift to 2cnd (harder then it has ever done, where my g/f said "what was that?"). I had been sitting in the parking lot idling for about 10 minutes..... and that was abnormal, so don't know if related to that, or previous issues? It only did that hard shift once. Coming home, it seemed to linger just a bit more than usual, before shifting up a gear.

The other strange thing is that I can hear a slow "double-tick" coming from under the drivetrain. Almost sounds like an electrical relay - but not sure (might be mechanical). It has about a second between each double-tick, and does not seem to change with rpm, and does it when in park. So.... you'll hear "tick-tick" ......pause...... "tick-tick" ......pause...... "tick-tick"...etc.

My warranty ran out in November, have 42K miles on the car now, so dreading taking it in without warranty coverage. The last thing replaced was at end of warranty, and was the air-pump and relay. Was replaced twice (the new replacement failed about 2 weeks after replacing at dealership).

Also, unsure if this last item is related (maybe not). At that time in November I had also complained about an occasional (only when car was cold at first part of day) a faint "pop-pop-pop" sound (not the "tick" sound described above) - dealer claimed could never replicate and claimed it was probably the air pump. I still heard it after the replacement, but they said they could never replicate it, and then said probably just the valvetrain when cold. That seemed to come from under the right front of the car, increasing with rpm, but only heard around 20 - 35 mph under load when cold.... after about 10 - 15 seconds would never happen again until car sat overnight. It sounded more like an "air" sound, or possibly a really small exhaust leak.... didn't quite sound like ticking valves.

Still no CEL either.

So.... now I think my car is acting up (maybe b/c it heard me saying I like the C63).

whipplem104

You most likely need the conductor plate on the valve body. The speed sensors fail and will cause you to go into limp mode. There will be a fault code in the transmission for the speed sensor. Have it checked out and if this is the cause do not let them tell you that you need the whole valve body. Also have them check to make sure there is no transmission fluid getting up to the tcu through the wiring.
Good luck.

AMGSC

subscribing

MarcusF

I agree with WhippleM104 sounds like a bad signal from the speed sensor. If you have a scanner, you can check the code. A year ago my car threw a P0715. A P0715 means the input speed sensor has malfunctioned. The input speed sensor is in the transmission. To get to it, the transmission pan is removed, remove the filter, remove the valve body, extract the plate that holds the input and output sensors, and then with the plate on the workbench, remove the bad sensor. In my case, the plate was cracked which resulted in a bad signal from the sensor.

My local dealer did it in 2 days without an appointment. While they were at it, they did the infamous "transmission wiring harness o-ring job". My o-ring wasn't leaking, but it's a $2 o-ring, and they were right there, so it made sense to do it. Total bill was about $800. This is the parts list:

electronics kit (plate) (part number 140-270-08-61) - $223.45
transmission pan gasket (part number 140-271-00-80) - $12.00
seal ring (part number 140-271-00-60) - $2.09
transmission fluid (part number 001-989-21-03-10) - 5 @ $14.50 each
Transmission oil filter (part number 140-277-00-95) - $15.50
Lock pin (part number 140-991-00-55) - $1.69
Spacer (part number 203-540-02-53) - $11.02

jknust

Hi all, thanks for the replies. It resurfaced again, this time a permanent limp mode. I got a reader, and you were right, the code is P0715 (only code thrown). So..... hopefully with that a straightforward repair based on what MarcusF posted.

Two quick questions:
- Should I have it towed (any harm driving 30 miles back roads to dealership for repair)?
- Any way to clear the limp mode.... I try clearing the code, but it stays in limp mode now - so I presume the part completely failed?

You guys all seemed spot on with the sight unseen diagnosis - good work!!!!!!

sdman

My daughter has an 2003 E320 wagon. Went into Limp Mode.
Ran a scan and code PO705 Transmission Range Sensor came up.

Can anyone tell me where the sensor is and is it a module or some type
of assembly.
The gear indicator doesn't show what gear it is in on the dash.

Any help would be appreciated.


Sam

ML500K

This just happen last night on my C32 while I was on the freeway picking up my mom from the airport, the car wouldn't shift passed fourth gear. I was like hmmm, third gear also shifted at 3000+rpm which i knew wasn't normal at all. Another issue i found previous to this was that it sorts of jerks when suddenly pressing the throttle half way when try to accelerate. I noticed this jerking issue about 2 days prior. Today I brought it in for a checkup and the fault pointed to a faulty transmission electric plate sensor. Natually the whole part needed to be changed. Part no. A140 270 11 61. I replaced that part, flush the tranny and put new oil and everything is working beautifully, shifts are very tight and clean now, no more jerking. When driving slowly I can shift from 3rd to 4th below 2K rpm.

One more note, this morning when leaving for work, I did the famous ecu reset and it allowed me to shift pass 4th gear, but still had the "jerking" when accelerating.

One thing good about living here is the labor is very very cheap, the bill was roughly 400 dollars. Most expensive was the electric plate, about 250. The greatest thing was that they did it in 2.5 hours while I was watching them ..hehe

Oh I just wanted to add that this electric plate part and the solenoids come in separately, my car had 6 of them, luckily they didn't need replacing. Most of the reputable Merc repair shops have
STAR for diagnosing issues, and i highly recommend using them to pinpoint the issue. My mechanic was able to see that faulty part number in question~

Cheers.