Hi Jumbojim,
How are you, did you eventually manage to sort out your battery problems? Having only just read this thread, I realise its a few days old now, so have you now resolved this issue? If so, then ignore my post, if not, then I will help you diagnose the problem. Firstly, don’t be confused with some of the acronyms and terminology; I’ll explain what they all are and their functionality later as we go on. I’ll ask you this question first before we go any further, have you by any chance removed or spilt any form of liquid on or near the ESM (electronic shifter module)- gear shift module to you, if so, then you have probably damaged the ESM unit as a result of a short circuit on the PCB. If you haven’t, then that’s fine.
Secondly - The CL’s electrical architecture is an extremely complex networked system and the ETCM, (electronic transmission control module) which is on the CAN C Bus - (also known as chassis CAN) receives all the input (command to start) signals before it initiates the starter lock-out relay to allow for the cranking process. The starter relay on the CL is actually located under the bonnet in the left hand side fusebox, adjacent to the brake servo/master cylinder. When you remove the cover, it’s the second relay down from the top and it should be green in colour. It’s a 5-pin relay and referred to as an SPDT - Single Pole Double Throw with corresponding pin terminal connections - 85, 86, 30, 87 and 87a. I’ll explain what they all are and where they go to later on.
The plus points at the moment are that you have a valid key signature and authorisation to crank the engine, hence, (you being able to turn the key to the crank position) so the EIS (electronic ignition switch)is communicating with the ECM (engine control module) over the CAN network, so that’s one element that we can rule out anyway. Also, you stated that the vehicle “occasionally” starts, so we cannot rule out the communication input link to the ETCM (electronic transmission control module) from the ESM (electronic selector module) which gives an input trigger signal as to its positions regarding “P” and “N” of the shift lever for crank/start safety reasons. What we don’t know at the moment is whether or not the ETCM is actually switching or activating the starter lock-out relay circuit. It’s not that difficult to assess and diagnose, but lets go one step at a time and I’ll take you through the process of how the system actually works and what to check and test.
For now though, here’s a really simple check/test that you can do if you can use a multimeter, remove the relay with the ignition switch in the “off” position and measure the resistance across the relay pin numbers 85 and 86, they should be within the region of between 68 to 72 ohms, (my own CL actually measures 71.4 ohms) if not, then replace the relay as a matter of course. Also, lightly tap the relay several times on some form of solid object and test it again, sometimes the coil windings inside the relay break or the electrical contact surfaces through pins 30 - 87/87a deteriorate and stick together resulting from arcing. It may very well be something really simple such as the relay, but who knows until we investigate. Also try and start the vehicle in the “P” and “N” positions to confirm the ETCM’s acceptance from the ESM - gearshift control module. You haven’t stated anything to the contrary, but can you move the gear selector lever through its full range? Is the solenoid valve actuating/clicking when you press the brake pedal, listen closely to it and let me know if it is?
Please Note - Fuse No. 37 is also responsible for the ETCM and the lock-out relays voltage supply and this is also located to the left of the starter lock-out relay in the o/side engine bay fusebox - (15 amp - blue fuse). Check this fuse for continuity, if it’s blown, then it will be the reason for the communication error between the ESM and the ETCM and the voltage supply to pin number 30 of the lock-out relay, no power - no communication - no crank. The EIS does in fact wake these modules up from sleep mode, and if they are not being powered, then they won’t communicate.
With the greatest respect, and I certainly wouldn’t wish to offend you, but there is no point whatsoever in me going any further with this if you don’t feel confident in working with vehicle electrics/electronics, it does get complicated as we go further on and you can do a considerable amount of damage to the vehicles electrical system and modules if you do make an error, and on a CL they can prove to be extremely expensive errors. Out of interest though, can you actually use a multimeter with any degree of confidence to confirm what I ask you to check/test? Come back to me and let me know what you want to do before I give you any further details, I would sooner you be really honest with me here. In the meantime, check out the above, these are really simple checks/tests and we may not need to go any deeper into this.
Out of curiosity though, what makes you think that the problem is related to the relay or starter solenoid anyway; where did you get this information from, many things can contribute to a none-start? I also noted that you have had the vehicle on a STAR machine with little or no success, with respect, it appears very strange to me how an Indy with an MB background can’t find this issue with such a sophisticated piece of diagnostic kit at his disposal.
Anyway, a list of what you have done up to now would prove to be very useful so I can either rule them in/out if you wish to proceed.
Best Regards,
Dash1
There are a lot of complex electronics on these later cars between ignition switch and starter solenoid which why I hesitate to say its that- but if STAR checks out.
