No Crank No Start Benz Cl600

Andrew Diagnostician Michigan Posted   Latest   Edited  
Unsolved
Driveability
2001 Mercedes-Benz CL600 5.8L 5-spd (722.6) — WDBPJ78J51A014052
P0121 — Throttle/Pedal Position Sensor/Switch "A" Circuit Range/Performance
No Crank / No Start

Hey Guys, This Benz came in initially with a symptom of a no crank no start. I checked this vehicle over and found a couple of issues. First issue was the battery was totally dead. It appears that if would not be this easy. I the electronic ignition switch and it appears to be requesting start for the vehicle. I checked the ECM and there appears to be no immobilizer faults or security functions keeping it from starting. I jumpered the relay and i would crank the vehicle by manually jumpering the circuit. I checked the control side of the relay and found no control voltage from the ecm. I checked scan data in the transmission and has me concerned . It says that the starter lockout contact is “closed”. I would assume this would keep it from starting. I attempted to jumper the circuit and get the vehicle to at least crank but had no such luck. The starter Lockout circuit is integrated into the transmission fluid temp circuit. This is quite odd but I guess this is the way they wanted to set it up for them. I removed the Transmission controller and inspected. I actually found tran fluid the had wicked its way inside the transmission controller. I replaced the transmission controller but found no change in the symptoms. I removed the valve body in the thought that the circuit was failed inside the transmission. Unfortunately there was nothing odd in there. The Circuit setup for the the starter lockout runs directly in series with the transmission fluid Temp sensor. The way it should work would be that when you shift into Park or Neutral the starter lockout solenoid PID goes from Closed to open and the vehicle should start. Not sure what is going on but it sure is frustrating. Any insight or help into this one would be much appreciated. 

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Interesting
Anthony Owner/Technician
California
Anthony
 

Conductor plate shorted, you're diag is right on point. 722.6 won't need to be coded.

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Phillip Diagnostician
Alaska
Phillip
 

Couple things. First I did not look at the diagram so I am assuming a little here. Next is the electronic steering lock working? What kind of signal is supposed to be getting to the transmission? Ground, voltage or a data signal?

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Marty Technician
California
Marty
 

220 chassis doesn't use a steering lock… Yes sounds like you need a trans conductor plate… You may want to verify the voltages at the TCM since there was oil intrusion at both the connectors (TCM and Trans valve body). See attached. Did notice you have current codes in ESP (CAN codes) and ME…Throttle codes can be an indication of module failure… Just for good measure make sure you check…

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Andrew Diagnostician
Michigan
Andrew
 

If I disconnect the Conductor plate connector at that switch Starter lockout switch then shouldn't it show open circuit?

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Marty Technician
California
Marty
 

Yes, what happens when you measure ohm value per test given in attachment 2 of last message? Check voltage value at TCM pin 34 when moving from P/N to gear? confirm ground at Pin 33 as well. If it never changes, run same test at conductor plug, back probe pin 4 for voltage pin 12 ground. If change occurs at plug then something is wrong with the oil intrusion wiring harness or…

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Andrew Diagnostician
Michigan
Andrew
 

I will check and verify those items and get back with you. Thanks

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Andrew Diagnostician
Michigan
Andrew
 

I don't have the resistance as specified. I do however have an obvious switch in the scan data when switching from P to R. What is weird is that I can see the obvious temp change when shifting from park to Drive and back I also can see the voltage changes on the scope. Do you happen to know what the input voltage should be on Pin 34?

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Marty Technician
California
Marty
 

The P/N signal value may be coming from the ESM/electronic shift module…I don't use that scan tool, I use Xentry , so I cant say for sure. I was unclear…I know you installed a TCM but have you installed a new ( quality/not Cheap EBAY special) Conductor plate? Where is this scope measured (?) at TCM or conductor plug at trans? Not sure as to voltage at Pin 34, but 5V sounds plausible. I'll try…

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Andrew Diagnostician
Michigan
Andrew
 

That would make sense that the park neutral value is coming from the esm but On the scan tool image it has the transmission temperature and it changes validating the circuit going from closed in drive/ reverse and reading temp to 19deg Celsius to 255 which I would think is open. The scope I sent was at the tcm connector back probing it. Pin 34 to ground and also got the same results from pin 34…

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Marty Technician
California
Marty
 

If I understand correctly, it sounds like we are back to the conductor plate… so far only 722.9 cars in shop today so unable to test pin 34, voltage but it sounds like you have too high resistance in the circuit. Ohm out to wiring from the tcm to the conductor plug. jumper the 2 wires for the on pins 4 and 12 if value is good you are gonna need a conductor plate…

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Andrew Diagnostician
Michigan
Andrew
 

Well, I plugged in a new conductor plate and checked for operation. I found the same results. Resistance value at the conductor plate connector Pin 4 and 12 is 960 Ohms and OL when switch is pressed for Starter lockout switch. On the Scan tool I get the same results as previously. I did notice that when I am watching the temperature reading measurement along with the Starter lockout status it…

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Terry Owner
Nevada
Terry
 

Does that car have a pedal position sensor with a cable going to it near the firewall. The only codes I see in ME for throttle is P0120 for any complaint. If it has that the voltages there are very sensitive values.

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Marty Technician
California
Marty
 

If are you referring to a mechanical cable like the 210 and the 163 chassis, No. Fully electronic throttle.

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Thanks
Marty Technician
California
Marty
 

Sorry for the delayed response. Are you measuring resistance with the TCM module connected? If so, the strange readings may be why the values don't make sense..? (measuring through the circuit board might result in a perceived implausible value..(?) Also just curious, is the used TCM the same part # as the original? What were your CAN High and low speed voltage readings? Throttle value is…

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Andrew Diagnostician
Michigan
Andrew
 

Hey Marty, I am measuring the Resistance value Directly from the new conductor plate on pins 4 and 12. This is with the Conductor plated female connector disconnected. The Can Is reading around 1.7V to 4.8V high is 4.8 to 1.7.

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Marty Technician
California
Marty
 

Base on info I have your CAN is not running at the correct voltage…I show spec should be 2.4V and 2.6V. Check the network terminating resistor value: with CAN asleep you should have 60ohms. I'm pretty sure you should be able to test at the ODB2 connector (pin 6 and 14/high and speed cans respectively) or the CAN X 18 and Z37/2 or 37/3 connectors at the left lower footwell/sill area…(prone to…

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Thanks
Andrew Diagnostician
Michigan
Andrew
 

Huh Very interesting, Thought I would come across some type of other issues with the CAN being of like that. Ill Check that later today. Thanks

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Andrew Diagnostician
Michigan
Andrew
   

Do you happen to have the Data Link connector Pin assignment? Also I actually have 2.3 and 2.6V. I grabbed the wrong image. Oops. I went to the car this morning and it decided to have reverted back to the previous no start no crank…

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Marty Technician
California
Marty
 

ALDL/X11/4 -obd2 connector (pin 6 and 14 high and low can respectively)

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Marty Technician
California
Marty
 

Took a closer look at your pattern, your voltages are off... there is some variations that a filter may clarify or maybe recheck your ground, but the pull up and down voltages should be based off of 5V and 0V. The pattern should be more square wave like…

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Terry Owner
Nevada
Terry
 

Do the trans positions show in the cluster ?

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Andrew Diagnostician
Michigan
Andrew
 

Yes they do

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Terry Owner
Nevada
Terry
 

>20K ohms in P or N, approx .5-2.5 K ohms in all other positions measured to pin 33.

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Andrew Diagnostician
Michigan
Andrew
 

Thanks Terry I saw the note thanks.

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