Electrical nightmare

[Broadleybenz]

Ok so I’ve been having intermittent starting issues and no coil light, had car plugged in and it kept losing signal with the ecu and got a code p2506
What wires am I checking to make sure no corrosion before I get the ecu checked out?
This car is having my eyes out. It’s so annoying, I’m struggling to get anyone out aswell who’s really good with mercs and the car is stuck on the drive
Thanks for any help

 

[mattkh]

I don't have a E320 cdi.
I would start with the basics. Is the battery fully charged.
There should be a relay for the glow plugs. Remove and clean the pins of this relay.

 

[Tony Dyson]

^+1, P2506 is power input signal out of parameters which is generally too high or low and not missing as you are interpreting.
A healthy car battery should read 12.6v when engine off and no greater than around 14.8v with the engine running, anything below 12.4 would need attention, either charging if the vehicle hasn't beet run for an extended period of time or perhaps replacement.

 

[Broadleybenz]

^+1, P2506 is power input signal out of parameters which is generally too high or low and not missing as you are interpreting.
A healthy car battery should read 12.6v when engine off and no greater than around 14.8v with the engine running, anything below 12.4 would need attention, either charging if the vehicle hasn't beet run for an extended period of time or perhaps replacement.

Would a glow plug relay do the above? Not let it crank, then cut out

 

[Tony Dyson]

It's entirely possible, I would still start with the battery and confirm I was dealing with a healthy supply in the first instance then move forward from there, just simply unplugging and reinserting control relays can re-establish corroded electrical connections and it's an easy check with nothing to lose!

 

[Broadleybenz]

It's entirely possible, I would still start with the battery and confirm I was dealing with a healthy supply in the first instance then move forward from there, just simply unplugging and reinserting control relays can re-establish corroded electrical connections and it's an easy check with nothing to lose!

Don’t suppose you no where the glow plug relay is on an 04 320 cdi w211
I’m totally new to mercs I’ve never really liked them to be honest but this one was off a mate so I thought I’ll give it a go and when it drives it’s very smooth so I’ll keep it for a while

 

[Tony Dyson]

I don't but I'm sure there are others who do who will be along soon.