2002 S430 W220.
This forum has been great in helping with our current situation of a no-crank situation. We have spent quite a lot of time on self-diagnosis and a couple of mechanic shops, so now would like to use a Star diagnostic system to help eliminate the remaining possible causes.

Is anyone in the Austin, Texas area willing to let us borrow/use their Star system ? We're actually closer to Bee Cave, west of Austin off of Hwy 71.
The help would be greatly appreciated, and willing to compensate the generosity of that individual too. We are also open to someone bringing the SDS to the vehicle, if that's more convenient.

Here's the history:
-Vehicle would not start after it was parked in a parking lot for a few mins.-Key turned all the way, gear knob also shifted freely-All lights on dash were turning on, but no crank-Swapped the starter relay with a similar looking relay we had as a spare, circuit diagram looked similar -- BIG Mistake
-Now even the lights on the dash would not come on,suspected short circuit.
-Battery tested fine at the parts store (realized this is not a good test anyway)
-Opened the passenger footwell to discover the 150A and 60A fuses were blown. Replaced them with a new set we found at the salvage yard.
-Now at least the dash lights came back on, but still did not crank
-Towed it to a shop, spent 30min of time to tell us we have a bad starter. I assumed we saved ourselves a lot of diagnosis.
-Wrong. We got a used starter (tested) replaced by a mobile mechanic and vehicle still did not start. Turns out the original starter was working.
-Now we don't trust that shop
-We bypassed the starter relay by shorting pins 30 and 87, and the car actually started! It was a relief to see the systems functioning.
-Further diagnosis indicated that the starter relay is not getting the signal from the computer (gear module, brake switch, ignition, EIS, etc). The other pins were getting power and ground as expected.
-Bought an icarsoft MB II OBD scanner to check the transmission gear selector status. We noticed that there was a discrepancy in the selector position and the actual transmission position, even with the car running.
-We also noticed that the car would only move forward, like the transmission was stuck in the "Drive" position.
-Now we just removed the transmission control module from the box where the starter relay was, only to see that the TCM was soaked in transmission fluid.
-Suspecting the common issue of ATF climbing up the harness from the connector at the transmission, probably new or from earlier.
-Opened the TCM, dried it, but still got a used one from the salvage yard and put it back into the car. Car still did not crank
-We also noticed that the brake system warning was on the display panel, which was strange. -Towed it to another shop, they found that the gear shifter rod was disengaged from something. They fixed it and told us that the gear now engages properly.
-At this point, the shop is saying that believe the ignition switch or module is faulty and not sending the pulse to the started relay.

So there we are, with 2 possibilities remaining on the no-crank condition:
1. The brake switch is faulty, hence the warning message, and not sending the signal to the starter relay.
2. The EIS needs to be replaced (as a set with the gear module) or a standalone programmed at the dealership.

We are hoping that the Star Diagnostic tool wil help determine the condition of the ignition system (EIS)
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Just get a matched set of key , ignition switch , shifter and ecu from a junked car . Must be a matched set as they are coded together

 

Thank you for that suggestion ,tusabes. Is it a straightforward DIY procedure to replace all the 3 units -- Ignition switch, Shifter, and ECU ? I can imagine the ECU is easy since it is in the fuse/relay box in the engine compartment on the passenger side.

Is it easy to determine if the Ignition switch or EIS is bad using the Star Diagnostic tool ? If not, then I would hate to ask a generous member to allow me to borrow it or drive to their place and not find out any more than what we already know.

BTW, here is another question: Would it be ok to drive the car if we bypass the starter relay and start the vehicle ? Trying to figure out if we need to tow the car everytime we have to move it to a shop or back home.

 

As long as the fans are working when you bypass it should be fine to drive

yes it’s a pretty straightforward swap lots of people have to do it

 

A "shade-tree" fix, but...

If everything works after you bypass the starter relay, what about installing a pushbutton to operate the starter relay, and call it good?

 

Thank you wallyp, The push-button idea is a good one, but we would need to get the wires from the fusebox to the interior.
We might do just that if we find some info on the easiest way to do it.

Still waiting for a good samaritan to let us use their Star Diagnostic system so we can rule out the EIS or change it altogether.
(Gentle reminder--we will compensate for it's use)