Roverdrive Posted November 9, 2020 Share Posted November 9, 2020 A quick question regarding the starting circuit on the 300tdi. Is it necessary to have the relay under the fuse panel, or is this purely for the immobiliser system? I know he earth of the relay is switched via the immobiliser. The wiring has been chopped about on my vehicle already so I was wondering if this could be removed to help trace an intermittent starting problem. As far as I can see the 200tdi does not have this relay, can anyone confirm this? cheers Quote Link to comment Share on other sites More sharing options...
Peaklander Posted November 9, 2020 Share Posted November 9, 2020 The starter relay coil is inhibited from energising, by the 10AS alarm unit behind the instruments. So the alarm must not be set. The switched output from the relay is then routed through the immobiliser which is at the front of the battery box and on to the starter solenoid at cranking (if the coil is allowed to energise). At the same time the immobiliser also sends +12V to the fuel solenoid. You can bypass this relay. The two signals that you need are a +12V at the IGN switch cranking position direct to the starter motor solenoid (spade terminal) and a +12V IGN ON at the injection pump fuel solenoid. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted November 9, 2020 Author Share Posted November 9, 2020 Cheers for that PL. I am happy with the wiring to change, the question was more a case of if the ignition switch is up to the task of directly operating the starter solenoid rather than using a relay. The existing alarm has already been ripped out along with the 10as by the previous owner(s). Quote Link to comment Share on other sites More sharing options...
Peaklander Posted November 9, 2020 Share Posted November 9, 2020 Oh OK, I missed that! Yes the little solenoid at the FIP will be smaller than the one in the relay, so it's no problem. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted November 9, 2020 Author Share Posted November 9, 2020 Nope talking about the starter motor solenoid Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted November 10, 2020 Share Posted November 10, 2020 The 200s and before have a relay in the Fuse box for the starter solenoid, I would reccomend you keep it's there is a significant difference in size of the wires running to and from the relay. Quote Link to comment Share on other sites More sharing options...
Peaklander Posted November 10, 2020 Share Posted November 10, 2020 Sorry I got the wrong solenoid. I have had my starter relay (300TDi) bypassed for five years and switch the starter solenoid off the ignition switch on a direct cable. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted November 10, 2020 Author Share Posted November 10, 2020 Vulcan Thanks for that. The only drawing I could find seemed to indicate there was no additional relay between the ignition switch and the starter solenoid hence the question. I’ll rewire the existing then, just ordered the correct colour cables. 1 Quote Link to comment Share on other sites More sharing options...
Peaklander Posted November 11, 2020 Share Posted November 11, 2020 Hi Roverdrive, I am a little confused by this thread (I know I helped confuse things by talking about the wrong solenoid). Are you referring to a 300 or 200TDi? You say that the drawing you have doesn't show a starter relay but my 1996 300TDi certainly does have one. The drawing I use is for a 97MY vehicle but even the oldest 300TDi drawing I have for a 1991-94 vehicle shows a starter relay. Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted November 12, 2020 Author Share Posted November 12, 2020 PL My vehicle is a 300 Tdi. The drawing I normally use is probably the same as yours for the 1997 MY. In my hunting for info, I found a drawing which indicated it was for a 200 Tdi which did not have the relay, hence my question. Needless to say I can’t find that on line drawing now! Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.