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Im hoping you guys can assist me in testing some solenoids. First time ever for me, so not quite sure where to start. I did some Googling, but I cant seem to find where all this testing is done. Might have overlooked it :-(
Anyway, Im stuck in limp mode on my W210 with a 722.606 tranny and my iCarsoft scanner gives me a error code of P0748, a generic code yes. The scanner says its "pressure control solenoid 'a' electrical". I know where the solenoid sits, but wanted to know how I go about testing it. Besides draining tranny fluid, removeing sump and all that. I got some diagrams, resistance values of individual solenoids and images from Google, suggesting various pinouts to check, but unsure of how to go about it all. Is all this done with ignition on or off? Will I be doing all tests by the 38pin connector etc.
I would greatly appreciate it if someone can give me a rundown of how this is suppose to be done, or even a link of how its done.
You want the ATSG 722.6 Service Manual pages 12 through 23. It's out there but beware of malware infested sites. Also available via Amazon for not much money and one-day delivery.
You should be seeing ~2.5 to 6.5 ohms resistance on the solenoids with exception of the TCC PWM solenoid which should read ~2.0 to 4.0 ohms.
You can test with the conductor plate out most easily. Testing at the connector on the side of the transmission would be a PITA and if you test at the TCM connector you also have to factor in the resistance of the electrical harness. Be sure to check for continuity end to end on the harness from the TCM to the transmission (and also for shorts to chassis) if your solenoids all appear good.
Last edited by bbirdwell; Sep 21, 2019 at 02:29 PM.
Typical when you neglect pilot bushing service.
Fluid goes into plug and then into TCU, making all kind of shorts and all kind of codes.
$10 for new bushing every 10 years can save you lot of head scratching.
The Comm signal between the tranny and the Tranny Control Module needs to be clean - and the miscommunication starts with the failure of the O-Ring internally at the tranny adapter plug - and in turn the trany fluid "wicks up" thru the wiring harness to contaminate the Tranny Control Module board.
Now - a Mercedes dealer would say "replace the TCM" - but the good news is with patient and correct effort this type of contamination can be remedied effectively and for about $25-$30
1. Purchase replacement tranny adapter plug - Genuine MB or Genuine Mopar (Crossfire) which is like $15 - do NOT buy a Retail Auto Parts Store China-no-name-quasi-name adapter plug - MB or MOPAR only !
2. Buy a $9 aerosol s[ray can of MAF Cleaner
3. Yes - replace the tranny Adapter Plug
4. Pull the TCM board from the engine compartment - "flood clean" both sides of the board - held on edge using the MAF cleaner to "flood" the contamination off the edge - thoroughly flood both sides - set board aside for air dry (do NOT heat dry).
Use anything convenient to mop use excess fluid in the board box and at the car connector for the board - then use MAF to spray clean the box and the car connector as well - let air dry.
This gets Comm cleaned up - so now any codes will be "real" rather than "false" codes caused by the contamination.
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