Sprinter 312D ignition problem-wont start

[Bill312D]

My van started fine this morning then my mate took the head unit out of it which is a bit dodgy, and i went to start the van again and none of the lights on the ignition would come on, i turned the key a few more times and they did, then on trying to turn the key to the final position to start the engine everything just went dead and the engine didn't even try to turn over. whilst the ehad unit was out my friend re attached a wire to the head unit from the main unit to the fancy pivoting face bit. then plugged it back in. Now when i turned the key the lights would flash on and off and the dials that come alive when the ignition comes on were flying up and down like the power was going on and off, and a funny clicky, on off sort of noise is coming formthe relays under the drivers seat, and then again everythign goes dead when i turn the key to start the engine. now alls orts of funny stuff is happening a buzzing noise fomr behind the clocks sounds when i push the hazard light button, my smartveg contorl box bleaps when the hea dlights are turned on and loads of weird stuff. The smart veg computer is soldered to a switched live and continuos live on the ignition barrel, but neither of these additons have crossed any circuits to my knowledge, and i did check them again, and all the fuses inthe box under the steering wheel appear to be fine, although some are mising, but these have never been there since i have woned the van. Anyonehave a clue whats going on?

 

[dava]

Phew! It's not realy clear here but I'll try as I not sure what Year etc etc. If it's newish then it's CAN so you just cant plug wires willy nilly. Under the speedo head is the imobilser unit( hope there's no TWOCas on here) and from what I've read you may have done that in, if it is then that will sting you and it's a MB fix, sorry. The flashing dash lights etc are related to low volatge, why, I dont konw as I'm not sure what you were trying to achieve and where you've put live feed's to and from. If you tried to start the van with the speedo out it will think your doing off with the van and shut down, so no go.

You could try disconnecting the battery and reconnect after a few mo's then lock and unlock using the the key 'plip' and see if it clears. All of this is assuming it's a current 2000 onwards merc.
Hope it helps.

 

[Bill312D]

The live and switched lve fees i have connected ave not caused the problem as they have run tropuble free for several weeks. it is a '98 not one of the new CDI models, and has an aftermarket immobiliser fitted. the van will bump start. also the headlights don't work, when turned on they came on for a tiny amount of time then went back off and at the same timethe cab interior light went off, then back on when the lights were turned off, the alarm sounds funny when it goes off, the indictors don;t flash when i turn the allarm on or off, but it still makes the noise. thats all i have noticed so far..

 

[Sprint'n'Go]

Purely a stab in the dark but very easy to check - make sure all the earth straps/battery connections are good. I have had an electrical fault with some spotlight wiring on the Landrover where a multimeter showed a good connection but as soon as a large current was drawn there was insufficient contact and hence no lights. Physically clean and remake all the connections to be sure. This could also relate to your lack of power problems if you are getting intermittent voltage fluctuations?

 

[Bill312D]

Thanks for the suggestion, I was sure something was shorting intermittently, but very quikckly behind the dash fomrthe noises it was making so me and a ate took most oft he dash out until we got to the clocks couldn't see any worn trough wires that could be shorting but foundt he wire to the (time) clock area a little loose pushed this back in properly and everything worked, all lights indicators worked spot on, no funny noises when turning ignition on or using stalks etc started up fine off the key several times and ran...i dunno if it was just that clock wire it seems a little small to have caused all that hassle...but it seems ok for now, touch wood. kinda releieved its fixed i was imagining a huge bill from the main dealer.

 

[Sprint'n'Go]

Thanks for the suggestion, I was sure something was shorting intermittently, but very quikckly behind the dash fomrthe noises it was making so me and a ate took most oft he dash out until we got to the clocks couldn't see any worn trough wires that could be shorting but foundt he wire to the (time) clock area a little loose pushed this back in properly and everything worked, all lights indicators worked spot on, no funny noises when turning ignition on or using stalks etc started up fine off the key several times and ran...i dunno if it was just that clock wire it seems a little small to have caused all that hassle...but it seems ok for now, touch wood. kinda releieved its fixed i was imagining a huge bill from the main dealer.

I hope this sorts out your other problem too. It will be a good result if it does, damned electronics

 

[dava]

Now I know whats what, take a look at the harness that runs along the top of the bulk head under the bonnet. This rubs through on the inlet manifold, yet another common fault. Also earth on the engine block, passenger side near starter and while your in there check the harnes that runs to the starter from rubbing through, all from memory now, so dont shoot the messenger. The black plastic bag next to the battery fills with water, check dry and clean to repair.
Hope it helps.

 

[Bill312D]

Right, will check them, and i finally found a local independant merc mechanic who will do commercials so its going to him wednesday hopefully to check for fault codes for this and the other high revs problem.

 

[dava]

Bill before you go throwing money at it, as I doubt he'll find any fault codes if what Isaid is the fault, just check, visually all I've said. If it's any of them then a competent person could sort it, if it's the bag filled up, then tipping it up the right way and allowing it to drain would do the trick and if it's wiring, then something simple as rapping insulating tape around the exposed wires would survise.
Hope it helps.

 

[Bill312D]

OK i'l check all you've said and any other wires I can see, Tommorow. Its very worrying how it was so devestating yet it stopped after mincing about with the dashboard for a bit but not actually messing with any wires.if ithappens ona journey or osmething i'll be ****ed off. although it will run if I bump it jus tiwht no lights of any kind hmm. will have a look and post back tommorow, thanks

 

[Bill312D]

I checked all the stuff you mentioned dava but it was all fine. went ot he merc guy today and he hooke dit up to STAR for free, which was nice of him and it came upw ith 2 faults 1 minor elctrical one which i can't remmeber and another for the fuel pump, so i am thinking that could be to do with fuel pressure...for the problem in my other thread.