The replacement relay diagram printed on the relay cover should look like the wiring diagram in terms of logic and pin arrangement. Large contacts (30 to 87)pass 12 V batt voltage directly to the stater when the coil contacts (86 -85)are energized. The problem I'm having is why 86 is powered which can only be given by the start position of the ign switch to the relay. Any relay you put in there with the same configuration, will still have the 86 powered at the relay base which shouldn't be at ign switch rest.
Can you take a picture of the diagram printed on the relay cover?

 

Baxtor,
There are two brown wires. Brown wire (N) on the ign switch is live/HOT before any switched positions. The diagram shows it. Yes, there is another Brown wire on the relay base going to pin 30. This is HOT all the time too and once the coil is energized, 30 -87 closes passing the 12V to the starter.
I am not sure what you mean by "BUT it should NOT be attached to 86, should be 30". The diagram does show a brown unswitched wire going to 30 as it should. It's waiting 12V at 30. The switched WY (White Yellow) wire out of the ign switch is the start position wire going to 86 as it should, but only powered during the start position. No voltage should be present at 86 with the ign switch in "OFF" or "Run" position.
Perhaps there is low current stray voltage which can still be read with w/ a meter but has no real current ability to actually pull the contacts enough for a real start. Unloaded circuits can be read with full voltage but with no real current available, will not pull the relay for proper start, only enough to power the coil slightly and draw little current, which could be the parasitic leak. Corroded ign switches can leak to other internal contacts.

 

OP had a problem with a relay and stated he had a battery voltage live brown wire terminating at 86 on the relay which should not be the case. That there are other brown wires is just clouding the water. Let's stick with the relay for now.
As l said the brown should not terminate at 86 but rather should terminate at 30.
You seem to be describing the operation and layout according to the wiring diagram but that is not the layout l understand the OP has.

 

 

Baxter,
"As l said the brown should not terminate at 86 but rather should terminate at 30.". The HOT Brown wire does terminate at 30, as you say and as it shows.That wire was never the issue as far as I know. The issue from the beginning was why the relay was warm which meant there was power at pin 86 and shouldn't be in the OFF position, which the OP confirmed with a meter. That 12 Volt power should not be at relay base pin 86 (WY) as I think we both agree. It should only be there when the switch is in the "Start" position momentarily and not at any other switch position. Not in OFF and not in Run position. I think we both agree with that too. As far as I can see, all the brown wires are going to where they are supposed to be. One brown wire (Hot) going to the switch as it should and the other brown wire(HOT) waiting at the heavy contacts of the relay base (30-87), ready to supply 12V to the starter when relay coil is energized. The problem as it has always been is why there is power measured at pin 86 when there shouldn't be in OFF position. That power can only get there from the switch area as that is the wire between the start position of the switch and the relay base pin 86.
If he finds the switch connector, and if he unplugs it and loses the unwanted power at 86, then we'll know the power was being delivered unwantedly through the ign switch and before the relay.
Hope that clears it up.

 

Can you confirm that pin 30 is hot and pin 86 is not powered? When you said that there was power on pin 86 of the relay base, were you getting the pin connectors numbers from the relay base? or from the pin positions of the wrong relay contacts which you thought were correct. I have been assuming you have been reading the proper pin contact numbers off of the relay base so that definitely pin 86 should NOT have power with switch off when measured.

 

looks like a type B relay was used in place of type A

 

l think the final post from OP will indicate where you and l were coming from. All good just looking from different angles.
Best regards

 

 

Just like to add a bit of an afterthought to this thread.
As best l can figure with the incorrect relay fitted l think the unswitched battery voltage running through relay coil would have been the warmth but it would also have held high current contacts contantly closed. This would mean allways closed contacts virtually hard wiring the starter directly through the ignition switch.
I would suggest keeping a close eye on the ignition switch as it may well have suffered considering the current involved.

 

 

Good outcome to all of this. Those pesky incorrect relays have been the issue of many problems I have encountered in the past. A friend's BMW had a similar problem where every time the rad fan would turn on due to the coolant switch for the fan to run, it would shut the engine down. Turns out he had recently replaced a relay for the air cond, which the fan circuit goes through the A/C on/off switch and relay. When he changed the relay, it was in the winter time so the engine never got hot enough to trigger the coolant switch for the fan so the problem never exposed itself..until the spring and summer. Same shape pin base but electrically very different relays.
I guess when troubleshooting, I should ask whether you are measuring on the relay base, which should match the diagram rather than measuring based on pin layout taken from an assumed proper relay, in the is case it was not.
It's all good .

 

Hoping you can help me a wee bit with a wiring diagram for the ignition switch that you sent a pic of to me some time ago. My ignition switch is identical but the small plug with two wires purple/white and purple/black to it has become disconnected and I can't for the life of me, see where it plugs into. I have just had my starter motor stop cranking when turning to position 3 on the switch and I'm thinking that I may have inadvertently kicked this connection apart as I had the lower cover off to access the fuse box. I don't know if this disconnected plug would lead to the problem with the starter or not. If I take a lead directly from the positive battery terminal to the starter solenoid terminal of the starter relay plug, the starter spins the engine no problem.
Thanks, Ian

 

Assuming you still need for the 95 4.0, Here are the Ign and start diagrams. I don't see a separate two wire connector to or from the Ign switch though.

 

 

i refer to the small two wire plug that is part of the harness on the switch??

 

I just realized that you have a V12 6.0. All of the wiring diagrams I have been referencing have been for a 95 4.0. I cannot tell without a proper diagram for your 6.0 what the smaller connector is for. There may be a difference in ignition switches between the 6.0 and 4.0. Now that the distinction is made, I may not be able to help you without your wiring diagram. Perhaps somebody else can help with access to a diagram.

 

Here is a link to the 1995 V12 Electrical Guide: http://www.jagrepair.com/images/Auto.../jul1996en.pdf

 

Thanks fellas for the wiring diagrams - with these I've managed to carry out a few more checks to see where the non-starting problem could lie but so far i'm still not there with a solution.
First thing I checked was the integrity of the starter motor by running a separate wire direct from the positive battery terminal to the starter motor relay terminal 87. This produced a healthy turning over of the engine by the starter motor but obviously it bypasses the other electronics necessary for the engine to actually start. So I assume from this that wiring connections from the starter relay terminal 87 to the starter motor are healthy.
Second check - terminal 30 on starter motor relay (brown wire) permanently live and steady 12.8 volts (should have said, a new fully charged battery installed and 3 different starter relays have been tried already)
Third check - measure voltage at terminal 86 from ignition switch. 0 volts at positions 1 and 2 but 12.8 volts when at start position 3. I have assumed from this that my ignition switch is also healthy.
Fourth check - at terminal 85 - there was no continuity to earth from this terminal with ignition switched on or off. I tested it both at the relay socket and either side of the RFD diode - still no continuity to earth. Question is - is this correct? I'd like to try it on a working vehicle. from the wiring diagram, it looks as though the wire goes from terminal 85 via the RFD2 diode to the start/inhibit switch in the gear selector then on to the security control module and then to earth. I have tried all these checks with the gear level in Park and in Neutral. I've also tried starting the car whilst wiggling the gear lever in neutral or park just to see if that worked but to no avail.

That is as far as I have got for now. I'd appreciate any feedback from anyone who has a better idea than me as to what to check next - although the start/inhibit switch may be a contender - after that I may be truly stuck!

Thanks, Ian

 

Ian,
I agree, to get the engine to start, not much has to happen except to be able to pull the start relay and let the relay do the work of spinning the starter motor..
Just so we are clear, it is the starter motor that you cannot get to spin, correct? Not that the starter spins but engine will not start/catch.
Zooming in on the "proper" wiring diagram this time(and again sorry for posting and referencing the 4.0 diagram before) the grounds differ from each model as to what conditions need to be met for the start rely to be pulled. I have inserted the proper diagram this time showing the ground path necessary as you have described in your text. I would ask you to bypass all of the "safeties" and place a temporary ground at the 85 terminal of the relay. This temporary ground will eliminate the Diode, the inhibit switch and the security module. All you need now is 12volts from the ign switch to the 86 terminal of the relay for the relay to be puled when turning the ign switch to Start.. see below.
You can then work back towards the real ground to find out if there is a wire, inhibit switch or security module that is not providing the ground,