Occasional No Start - But always starts on 2nd Attempt

ncos

Member
Whats the voltage at the battery with the engine running? Could be a charging issue as well.
Charging voltages look solid > 14V

I'm pretty sure that it's charging fine. I don't have access to the van right now, but will take some resting current measurements when I get it back.
 

mtlsimon

New member
I’m kind of new to the sprinter world but I noticed that if I stop the engine but let the key on accessories position then if I try to start the engine it won’t work, all the lights in the dash comes on even the glow plug, but when I turn the key to crank the engine nothing happen, like in your case!

So I have to cycle back the key to off And then it would start as normal.

It kinda freak me off first but I guess this is normal and due to the rfid key

Good luck ;)
 

Cheyenne

UK 2004 T1N 313CDi
I’m kind of new to the sprinter world but I noticed that if I stop the engine but let the key on accessories position then if I try to start the engine it won’t work, all the lights in the dash comes on even the glow plug, but when I turn the key to crank the engine nothing happen, like in your case!

So I have to cycle back the key to off And then it would start as normal.

It kinda freak me off first but I guess this is normal and due to the rfid key

Good luck ;)
That behaviour is 'as designed' by Mother Benz. It is purely mechanical in the ignition lock and is nothing to do with the RFID.

It is to prevent you inadvertently turning the key to crank whilst the engine is running, say you accidentally turned it the wrong way when trying to shut the engine off, and hence prevent damage to the starter/ring gear.

Keith.
 

Nautamaran

2004 140” HRC 2500 (Crewed)
That behaviour is 'as designed' by Mother Benz. It is purely mechanical in the ignition lock and is nothing to do with the RFID.

It is to prevent you inadvertently turning the key to crank whilst the engine is running, say you accidentally turned it the wrong way when trying to shut the engine off, and hence prevent damage to the starter/ring gear.

Keith.
You’re right, but I’ve always considered this mechanical interlock an act of overkill since the key is only requesting that the ECM crank the starter (the key’s signal is required to power the starter solenoid, but it’s the ECM that grounds the Start Relay coil to send that power).
The ECM has the flywheel position sensor so it knows if the engine is spinning or not, and could simply exercise its veto and not crank a spinning engine. Having to turn the key all the way back to “off” to crank just means my radio and Espar need to reinitialize.
One of the quirks I tolerate for standing head room and 20mpg :cheers:
-dave
 

autostaretx

Erratic Member
The starter lock out in the ignition assembly is probably leftover from when the T1Ns had much simpler electronics.
I think the argument could be made that the T1N *never* had (much) "simpler" electronics.

Case in point: the ECM now has only 2 connectors. In "the old days" it had five.

--dick
p.s. total possible pin locations (not all are used): new: 141 old: 134
pins used: new: 82, old: 74
:idunno:
 
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ncos

Member
You might consider adding some test lights. A bit of description is in this thread. I'll start you here. Also check post #33.
https://sprinter-source.com/forum/showthread.php?p=703103#post703103
vic
Hey Aqua,

I finally got a hold of some 12V panel mount leds. I was going to repurpose an altoid's tin to hold them and stick them somewhere on the dash. I've got room for more than 2 (probably 6 total)...do you have any other recommended test lights I should wire up while I'm at it?
 

ncos

Member
You might consider adding some test lights. A bit of description is in this thread. I'll start you here. Also check post #33.

https://sprinter-source.com/forum/showthread.php?p=703103#post703103

vic
So I added two test lights, as recommended. For a week or two, the symptoms never presented which led me to think installing the test lights was enough to seat an improperly seated test relay.

BUT...it has now resurfaced: The test light connected to the start relay coil is always lit when it should be. When the no-start-no-crank occurs, the test light attached to pin 87 of start relay does NOT light. Is this enough to indict the ignition switch such that I should go ahead and replace it, or is there something else I should look into?

Maybe related?: My "key lock" function does not work (see page 21-168 of service manual). I can remove the key without putting the vehicle in park.
 

Midwestdrifter

Engineer In Residence
The ECM supplies the 12V and ground to the relays coil. The Ignition switch Supplies the power to terminal 87.

If the relay coil is getting power from the ECM, that means the ECM is seeing 12V from the ignition switch(s) start contacts. Since 87 on the relay is not being energized, it may indicate a wiring fault somewhere. Though the ignition switch may be faulty and has high resistance?
 

Cheyenne

UK 2004 T1N 313CDi
Have you tried keeping a scanner connected and checking for correct operation of the start command signals when cranking?

A possibility may be the gear shift problem you mentioned as if the ECU cannot confirm the GSM is in P (or N) then it will not allow a start.

Keith.
 

ncos

Member
Have you tried keeping a scanner connected and checking for correct operation of the start command signals when cranking?

A possibility may be the gear shift problem you mentioned as if the ECU cannot confirm the GSM is in P (or N) then it will not allow a start.

Keith.
I'll pay close attention, but i'm about 99.9% sure the dash indicates 'P' prior to these no-starts which suggests the SLA is reporting the correct position.

I have an Autel but really haven't used it. Is there a particular menu or signal I should be looking at? Based on what was said previously in this thread, since I'm not seeing a "start error" I was ruling out permission based stuff.
 

Aqua Puttana

Poly - Thread Finder
I'll start with this first so it doesn't get lost.

Maybe related?: My "key lock" function does not work (see page 21-168 of service manual). I can remove the key without putting the vehicle in park.
I can't say whether it is related or not. It could, might be a related symptom. It may be worth correcting that in case it is related. I believe that the basic interlock is a cable operation. If the condition is repeatable enough, you might try moving the shift lever to Neutral for all of starting operations. If the problem doesn't present, then the key retention feature/adjustment *may* be related. That said, moving or adding test lights as I describe further on should avoid repairing the key related mechanical problem [unnecessarily, for the present problem anyway].

So I added two test lights, as recommended. For a week or two, the symptoms never presented which led me to think installing the test lights was enough to seat an improperly seated test relay.
The test lights should help.

BUT...it has now resurfaced: The test light connected to the start relay coil is always lit when it should be.
S108 is getting power as it should to feed the Start Relay and Fuel Pump Relay when the Ignition Switch is in Position 2 or 3.


When the no-start-no-crank occurs, the test light attached to pin 87 of start relay does NOT light. Is this enough to indict the ignition switch such that I should go ahead and replace it, or is there something else I should look into?
:hmmm:
Without S219 getting power, the ECM aka ECU won't get the Start Enable signal. Or maybe the ECM does get the signal, but not to where your test light is connected. It could be possible that S219 is a problem.

Moving, or adding a test light to the FB#1 C3-3 12 VT wire should answer the S219 possibility.

Answer for orange highlight above.
Not necessarily. The 12 VT Violet wire is fed by the ignition switch 14 BK/YL through the FB#1. IN = FB#1 C2-2. OUT = FB#1 C3-3. The next move for me would be to put a test light on the BK/YL wire. That should narrow it down to either the Ignition Switch, or something related to the FB#1 circuit, not necessarily the FB#1 proper though. The 14 BK/YL wire is likely only available to you at the Ignition Switch proper.

8w-20-06StartFuelRelaywNotes3.jpg

8w-10-13IgnitionSwitchwNotes01.jpg

:2cents: vic
 
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ncos

Member
Well...I went ahead and ordered an ignition switch just in case. I figure if I'm going that far into the column I should just replace it (if its easy).

So...looking around the forum and the service manual (and internet) I couldn't find anything about how to replace the ignition switch. Does anyone know of a write up or if I missed something in the service manual?

Nate
 

autostaretx

Erratic Member
Removal of the ignition key cylinder is in the "steering column" section of the manual.
I have to admit i don't see specific instructions for the *switch* (maybe they think it's obvious?)

The shift-lock cable is covered in the Transmission section.

--dick
 

Aqua Puttana

Poly - Thread Finder
While parked and waiting for someone today I messed around with the shift/ignition interlock. I wasn't certain if there was an electrical interlock involved. My conclusion is that it is all mechanical/position related through the cable.

FWIW.
I doubt that there is any electrical interlock involved with the shifter/ignition/key retention/start design.

:cheers: vic
 
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