jimh Posted May 3, 2018 Share Posted May 3, 2018 My 620R broke down at Brands Hatch today, apologies if this impacted you.Anyway, the car is blowing a 20a fuse which seems to power the fuel pump etc.Tried disconnecting the wheel speed sensor but didn't make any difference.Would be grateful for any ideas?The car starts for a couple of seconds so the immobilizer and starter circuits seem ok. No power to any of the instruments at any time. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 3, 2018 Member Share Posted May 3, 2018 Any recent work?Has it been drowned?Do you already have a wiring diagram and fuse layout that match the car? Let me know if not.And a multimeter?...There's a recurrently reported problem on some K ECUs that is fixed by using a 30 A fuse rather than 20 A but I don't think I've read anything similar with Duratecs.Jonathan Link to comment Share on other sites More sharing options...
7 wonders of the world Posted May 3, 2018 Share Posted May 3, 2018 Check that 20amp is the correct fuse and has not been put in by mistake - some models had an uprated fuse ISTRIf not then access the wiring diagram if you can and find what else the 20amp fuse feeds, disconnect them all then reconnect one by one until the fault occurs, then you can check the component, control or the harness for faults.Write down what to test and find so you have it for reference later in the process if required. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 3, 2018 Member Share Posted May 3, 2018 No power to any of the instruments at any time.Are these traditional separate instruments?Jonathan Link to comment Share on other sites More sharing options...
jimh Posted May 3, 2018 Author Share Posted May 3, 2018 The car has not been used in the wet recently.The instruments are standard 620R so no stack cash etc, just gauges and digital gear indicator. The Speedo also remains stuck at the speed when it failed Link to comment Share on other sites More sharing options...
rj Posted May 4, 2018 Share Posted May 4, 2018 What happens if you pull the fuel pump plug? Does it still blow the fuse?Unfortunately I don't have a wiring diagram for a 620R so it's only blind guessing.JK,I presume you don't have the diagram for the 620R? Link to comment Share on other sites More sharing options...
jimh Posted May 4, 2018 Author Share Posted May 4, 2018 It initially looks like it is a short in the wiring to the rear wheel speed sensor. Link to comment Share on other sites More sharing options...
rj Posted May 4, 2018 Share Posted May 4, 2018 You can use a headlamp bulb as "fuse" whilst searching for the fault. Link to comment Share on other sites More sharing options...
CharlesElliott Posted May 4, 2018 Share Posted May 4, 2018 The symptoms are those of a rear wheel sensor short. Racers like me remove them to avoid any chance of that issue happening! Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 12, 2018 Member Share Posted May 12, 2018 With Charles' advice and that stuck speedo I'd disconnect that circuit in as many places as possible and see what difference that makes.Otherwise with a non-obvious cause I'd pull the fuses on everything and restore the circuits one by one until something didn't work as it should.Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 12, 2018 Member Share Posted May 12, 2018 I presume you don't have the diagram for the 620R?I don't know... would you expect it to be different from the current factory Duratec diagram?Jonathan Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 15, 2018 Member Share Posted May 15, 2018 How's it going? And are you following jake's incident?Jonathan Link to comment Share on other sites More sharing options...
jimh Posted May 17, 2018 Author Share Posted May 17, 2018 My car is back running again but I don't really know what caused the issue.I think we have ruled out the speed sensor because even with this unplugged it continued to blow the instrument fuse. Once the instruments were unplugged then the car started and worked fine albeit without any instruments. Strangely when reconnected everything continued to work and the fault has gone away. The instruments were disconnected at the large plug adjacent to the fuse box under the dash.Slightly concerned that the original fuse that blew was a 20a when the wiring diagram calls for a 7.5a fuse in that location. Currently using a 10a just now. Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 17, 2018 Member Share Posted May 17, 2018 Thanks for the update.Where did you disconnect the sensor, and could there be an intermittent fault in that circuit in a more central location?What does the Handbook say that the blown fuse supplies?Jonathan Link to comment Share on other sites More sharing options...
ChrisC Posted May 17, 2018 Share Posted May 17, 2018 I would love to have an up to date wiring diagram for my 360R. The wiring diagrams in the build manuals are nearly correct, but the connectors have changed and components like the MFU have been removed from the car (not the diagram) :( Link to comment Share on other sites More sharing options...
Member Jonathan Kay Posted May 17, 2018 Member Share Posted May 17, 2018 Have you got "Version 02.2015.b" for "270, 360 and 420 plus Academy"?Jonathan Link to comment Share on other sites More sharing options...
jimh Posted May 17, 2018 Author Share Posted May 17, 2018 The speed sensor was just disconnected at the plug by the right rear wheel, however the fuses continued to consistently blow following this and all the instruments remained off.I think that fuse supplies all the instrument power including the speed sensor so the wiring goes everywhere.CC suggested to me that it could have been a short within the instrument power plug.I need to use the car and see if it fails again, at least I know that unplugging the instruments may get me going again. Link to comment Share on other sites More sharing options...
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