Where is the safety switch for the shift lever in an automatic transmission. The switch i'm talking about is where if the shift lever is not in Park it will not let the engine start. Is it in the console or is it under the car on the transmission? "Or do I know what the heck I'm talking about?"

 

Take the center console out (that will keep you busy...) the SLA (shift lever assembly) has two or three switches: Park, Reverse and I think Neutral. They are wired to the module in the SLA that talks to the transmission control module over a CAN BUS.

Once you get the console out, you can get to the SLA, I have NO idea how serviceable it is.

 

It is not really serviceable. Also, there is no dedicated switch for safety. When there is a no start, the first place to look is RCM, then possibly Pulse Module and once you have exhausted those, then look towards SKREEM issues. This is assuming you have first looked to see if the fuses are all good.

 

First time ,with all the help that has been offered, that the pulse module has been suggested? Where is it located and how is it checked? Today is day 5 of no troubles with the car starting. I'll have to look up the pulse module and how it works in the starting skeem of things. Thanks

 

Get into the underhood fuse box. Remove inner cover. Pry up the fuse carrier, the pulse module is below the fuses.
If you are going to work on the car, download the service manual so you know where things are. The sketches of the modules are crappy, but better than nothing.

A short you can do is to open the pulse module and press the relay closed. The starter will engage unless the starter or battery is bad.
With key on, if the engine starts this way, you have a clutch/park interlock issue or a bad pulse module.

 

Are you stating that the car can engage the starter when not in Park or Neutral?
THere is a CAN BUS from the SLA to the TCM to the ECU, I'd assumed the shift position was passed on to the ECU as i, I know very well, will prevent starter engagement thru the pulse module for various reasons, the shift being in gear being one of them.

You are going to have a hell of a time telling me that the system does not verify shift position when engaging the starter.

 

There is no actual safety switch. Instead, the shifter position is communicated via CAN bus to the ECU, which, in conjunction with the SKREEM, will grant Drive Authority, and hence the ability to start. The starter signal does originate in the ignition switch, but that is a signal that goes to the ECU, and the ECU decides whether or not the starter may be engaged. Hence Soft Start is an option that can be enabled (and is on many automatic Crossfires), and why the starter will not engage when the engine is already running.

 

This is day 6 of no problem starting my car. Everything is working as it should. I'd guess it's kinda hard to troubleshoot something that is working correctly. ( This is driving me crazy. Hard to trust this car that it might leave me stranded somewhere! Other than that this car really runs good and fun! )

 

That was my point.

 

I am having issues along these same lines. Bought from auction and it would not get out of limp on the way home and was having issues in and out of SLA positions. Gear display in dash was blank - now it wont start.

error codes -

P2300 (CAN Communication Faulty)
P2313 (Shift Lever Position Invalid)
P240C (SLA CAN Message Incorrect)

I have replaced the SLA (used)(problem persists) and checked the RCM for bad soldering or burns (looked spanking new with great soldering).
New Battery. Alternator looks new.
There is an aftermarket radio system that might not have proper grounding.
Have not checked the transmission fluid.

Any more details on that starter bypass?
could this be a grounding issue somewhere?
does a blacked out gear display indicate anything? this seems unique in research.

 

Many have "checked" the RCM and later find that it indeed was the problem . I would start by replacing the RCM (having a spare is a very good idea) The Mercedes # 170 545 03 05 and the Standard brand (which you will probably find for the least $) part # RY1562.
Get the trans fluid checked.

 

No one can help you. "Now it won't start" is a meaningless statement.

Does the starter engage or not? If not, leave key at "ON" for 30 seconds, does the engine fan run fast? If so, replace or repair the RCM. If fan does not run fast and starter will not engage, we have more work to do to diagnose the car.
IF the starter engages and engine wont start, we also have more work to do (that is, more questions to ask) to diagnose the car.

GIve us a direction: Tell us if the starter is engaging or not.

 

You almost certainly have a failed RCM. Your exact symptoms have been described in other threads, including the blacked out gear display. Get a new RCM. Looks often do not tell the story of a burnt coil or carboned up contacts.

 

Thank you guys so much for the help.

I couldn't find the blacked out box gear indicator on this forum, excuse my lack of search prowess.

I'm ordering the new rcm and will post back. If problems persist I will try to be much more detailed in the follow up. Thanks again

 

Given the high failure rate of RCMs (I have had three ROadsters, two of the three experienced failed RCMs eventually) its a good idea to order a new one, put it in and send the old one to DJ for reworking.
THEN, you have a spare for the next time it fails, cause they all seem to fail. THey plug in without tools, super easy. No need to disconnect the battery, just replace it.

 

Got the new RCU unit from a dealership. Swapped and no help. same black box no start

Turn the key to on and I hear the pump near the tank for a few seconds. And the dash peeps. Turn the key to start and nothing.

Gear indicator in the instrument panel has a black box but it won't let me take the key back unless the sla is in park.

What's my next step?

​​​​​​

 

I'd be looking at all fuses related to the TCU.

 

Looking at the manual it mentions CAN errors with the transmission. Gives a different code but I was reading with obd. Recommends swapping instrument panel if the drb III diagnostic and reset doesn't work.

All fuses I could find had continuity. Looking at the schematics I feel like it could be anything from a faulty ground to low tx fluid to a bad instrument panel. Any suggestions would be helped and followed ✌️

 

It's not low transmission fluid. You need a DRBIII or SDS to do this properly. Will tag @Dave2302 to get his professional opinion.

 

That was my thought. First troubleshooting step was resetting and checking communications. Are there any good alternatives to purchasing an actual unit? I saw some posts and links for good alternatives but first hand experience would be better. Thanks again for all the effort.