Hi guys, looking for any advice on mk3 rs265.. Had to replace the battery as an issues started with slow cranking to then testing battery and finding its dead (en/amps 260 should be 700-760). So installed the new battery no issues. I’ve gone to start the car and now it won’t crank at all. Put the old battery on and does the same thing. Somehow it’s shit itself whilst doing the battery change. I have no ignition or crank but the car does recognise the key in the slot and does lock and unlock The battery was changed how it’s suppose to be so there was no short/spark. I’ve replaced the earth cable as mine was corroded thinking the ecu wasn’t earthing properly and maybe moving it to install the battery disturbed it, but still no joy. I have check all fuses (under glove box, upc fuses and fuses behind the battery) and all are fine. Any help or direction would be appreciated TIA
Make sure all connections to the Battery Disconnect Module (1144) are connected to correct terminal post etc and are tight. Also on the module there is a small 5Amp fuse (F7), that supplies power to the battery current sensor unit. Any chance you shorted a wire? From what I remember it's on the side of the module, under a soft black rubber cover - a bitch to find If no chance you shorted a wire, then likely you've forgot a wire to connect (speaking from experience), or connected it in the wrong place
Hi! Sorry for the late reply as I’ve not had time to check the car over however I did read your comment and double checked that over the weekend just gone. I managed to open that battery module and could see no breaks in the wire. Also done a continuity test as well which showed a current. Opened up the UCH fuse box and checked over all the fuses as well as the motherboard. Everything looked fine. Any help with this will be massively appreciated.
I've attached 2 schematics for the F4R874 - each is slightly different which surprises me; the one that shows two cables going to starter motor seems to make more sense. Basically 2 cables onto starter motor - main cable - control signal (as solenoid switch is on the starter motor) Can you see if you have 12V on the big supply cable at the starter motor. Use your -ve ground point actually on the starter motor body. If you do then it must be the signal cable that is the problem. To confirm this get someone pressing start button and measure if 12V - first at starter motor - then at the battery disconnect module (discount the cable between the two) So if no starter signal getting thru, and you can get auxiliaries powering up with the keycard, sounds like one (or more) of the shitload of start permissives is not true. eg brake pedal pressed, etc.. Then to solve this problem you need Clip or DDT4ALL to look at what's locking you out of a start
Also by way of example, the DDT4ALL page to help troubleshoot. Maybe see if someone near you has it and they can assist. Also don't "write" with DDT4ALL (read is fine) unless you really know what you are doing
