Beached Benz...AGAIN? (GL450 No-Crank)

hi everyone welcome back to Pine Hollow out of Diagnostics we're back on the 2012 Mercedes GL I think it's a 450. I wish I was working on this thing but this thing is a no crank again owner says his wife drove it here parked it and it never cranked first thing obviously we'll start with a Health Report on the thing tool Pros and we have some communication faults direct select electronic ignition transmission engine control unit the ECM says no can message is received from the direct select no count message from transmission no can message from steering com no can message from traction control no can message from Air Conditioning yeah the easy-s Central Gateway or instrument cluster okay steering calm cam communication so we're dealing with communication fault on the high speed Network now you might ask how is the engine computer how are all these modules talking with the scanner and they can't talk to each other this is very similar to the beached whale Mercedes AMG the 2010 that we diagnosed a little while back and that turned out to be a bad engine computer we scoped the networks everything was fine the can signals look great but the engine computer just went nuts and was setting all these communication codes so since the fall is present let's just clear all the dtc's out I have the report saved and we'll try to crank it and see what comes back right away we'll Chase those codes we've got all data pulled up look at some wiring diagrams for the information bus and go from there so place your bets now this is going to be a bad engine computer perhaps that's kind of my gut feeling but below we'll see all right so we're dealing with a problem on can c and that's the one we were dealing with last time if you remember well you'll you'll have to go watch the video but this bus was down because of you'll have to go watch the video so I want to get a scope on this the can comb connector passenger side voltage distribution can't see connector let's get to that put a scope on it let's just try to start once nothing there let me scan it one more time all right we've got two channels over there on the can distribution high and low here's what we're seeing so just seems like normal packets are not shorted to battery or shorted to ground there is quite a bit of ringing when this module tries to communicate like right here it's something weird now if we bring these down it's going to match them up they should be mirror images bias voltage is at two and a half that's good it's like right there is a good packet but what about these right here a lot of ringing let's just play it again and the code scan didn't show anything weird see turn off keep playing the uh the scope see if it times out yep sure did yep turned off just fine why is it not cranking hmm it's going to ECM read fault code no dtcs driver authorization let's see is it disabling itself yes yes everything's good transport protection detached let's see what the electronic ignition lock is saying the ezl oh where's it the Eis electronic ignition switch let's read some data in there no dtcs access authorization everything's everything looks good terminal 15 and terminal 50. earnings on start and stop button keyless go pressed see terminal 15x can on that's off and that's off you know terminal 50 I think is the starter let's see off on and then crank you see terminal 50 is on they release it if I try to crank it again it won't let me so so far I don't know where all those codes are all about cleared everything out it still doesn't crank but it's not setting any communication codes and the can signals look just fine on the scope let's take a wiring look at the wiring diagram of the starting Circuit of this term output terminal 50 Mercedes all right so here is the diagram of the starting circuit here's a starter and it's fed by see there's terminal 50. starter relay engine compartment fuse box and let's see here how did all time circuit 15 relay feeds the starter relay hot width engine circuit 87 energized that's the control and the control is grounded by the prevention control a engine computer so let's find let's find this relay do some basic checks there all right so here's our relay box and the assignment here letter I is starter relay that's right in the corner by the stud this one right here let's pull it out five pin and get a test light check some voltages all right so back to the diagram 30 and 87 are always the load side so Tesla across 30 and 87 with the key on we have a nice bright white okay that's interesting I mean that's good so see that goes to the starter I'm just checking continuity through the starter on the load side and the other pin [Applause] sure test light works so this must be pin um you know that's the feed that's pin 30. so if we jump these two together with the key on will the car start let's try that and then we'll go after the control side if there's a problem so fuse jumper ready keys on nothing let's check the amperage on there I didn't hear anything click 10 amps starter is not clicking okay so at this point it looks like a bad starter what let's check the control side W pins 85 and 86. when we crank the car that should light up a test light across these two pins right here to switch on that relay so this is basic relay testing load and control side so let me put this right here we can see it through the windshield whenever terminal 50 says on the test light should light up let's see yes test light's on Terminal 50 on now if we try to crank it again you see it went off and crank it it will not let you do it the second time it looks like the starter on this thing's junk if I can locate it and we'll we can manually just jump those two pins together hit it with a hammer see if this thing fires up and runs it's gonna be a bad starter why do we have all those communication codes that blows my mind all right so I found the starter it is visible through this hole right here there it is so I'm gonna get a pry bar and smack that solenoid and see if we can get this thing to start up all right so we're manually gonna energize the starter I got extension leads so I can well I hear hopefully this thing doesn't run me over and uh let me get a good angle so starter motor I'm just gonna bang a couple times trying my manual test let's see ah so clicked no more click we have to make sure the engine's not seized up foreign yes it does have oil in it try that again [Music] okay here we go again we can always monitor the current going to the solenoid I'm gonna go 10 amps let me just let it run through there all right foreign the starter but fairly straightforward diagnosis it clicked once no sense in beating a dead Mercedes to death here laughs here to click no spinny all right that's under the diagnosis I'm sure the owner will install his own starter for his wife make her happy um not a fun Network problem this time but I'm sure it'll be back for something else thanks a lot for watching we'll see on the next one bye

Channel: Pine Hollow Auto Diagnostics

Views: 55,370

Keywords: Mercedes, crank, start, relay, CAN, communication, key, engine, dead, euro, module, starter

Id: HU5vGf2Q35I

Length: 15min 53sec (953 seconds)

Published: Sun Jul 09 2023