MG-Rover Technical and Information Pages

Replacing the YXB-100350 Ignition Switch

An annoying problem encountered some time ago, was initially with a suspected fault within the sealed unit of the vehicles ignition switch, no dash panel lights, just the sound of the fuel pump being primed for the starting procedure. Only time to get a panel display, was with initiating 'quick and positive' turns of the ignition key, panel lights would then activate, but would only catch on maybe just a couple of times out of several attempts by using this procedure. So at this early stage, took the first and best option of checking, and ruling out all of the other possible ignition related problems, including the condition of all earthing points etc.  

Alternator connections were first re-checked, although this was a recent new unit we had fitted a few months back, along with condition of the 12volt battery, plus a check on all related earthing points, including crimping a new spade connector to the starter motor. However doing this made no difference to the vehicles starting problem. The final option, was now to test for a faulty switch, To do this the cabin fuse panel was  removed so as to reach in to gain access to the base of the switch. With the ignition switched on, and just using hand pressure on switch base against bottom of the key barrel will only activate the starting procedure, you have a faulty ignition switch. We decided to replace ours.   

To fit a new YXB-100350 ignition switch, steering wheel is lowered down, both column covers removed, top part will just prise off, the bottom part is secured with 3 screws, cabin fuse box lid also needs removing, the switch is attached to bottom of key barrel with two small cross head screws...access to these is slightly difficult, so removal of the dial surround which is secured with 4 screws, created an easier working area The ignition key barrel which is factory secured to the steering column with shear bolts, did not need to be removed during the whole process.

Dial surround removed for easy access

This helped gaining access to the 2 small cross head screws that hold the ignition switch to the lower part of the key barrel, of which enabled us, working in a tight space, to get to the top cross head screw..

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YXB-100350 Ignition switch/multi-connector

At this stage, and with the multi-connector now attached to the new switch, it can now be slipped back into the lower half of the key barrel and secured with using the same two cross head screws.

A question often asked, is it ok to oil my ignition key to give it a smoother action when inserted into the ignition key barrel. When the key has been lightly oiled, or given a light smear of graphite grease to both the serated edges, and then inserted into the key barrel, it helps loosen each of the individual key security spring loaded digits within the key barrel, so giving a much more smoother and glide free key action, taking note that this method given to the 200 and ZR only applies to my own personal experience, and should not be relied upon.

Ignition Switch Information  

What's inside the YXB-100350 ignition switch

Ignition switch shown below after being dismantled with top part, lower part, and rotor removed. Having previously stated this was a sealed unit. further investigation shows that the whole unit is just clipped together, so can be dis-assembled with extreme care and attention, the only parts removable as shown below, is the rotating key position selector, from the centre spindle, and the small spring loaded guide selector.  

YXB-100350 ignition switch

Located around the outer edge are various contacts a total of 5 which activates any of the key positions thats being selected, to achieve this the lower part of the rotor has corresponding grooves and slots which will open and close each contact as key is being turned during engine start and stop procedures. The guide selector corresponds to indents
under the collar of the rotor, giving the clicking sound as key is turned to any of the positions that are being selected.  

To re-assemble, the spring loaded guide selector is placed back first, then the rotating selector is then placed onto the centre spindle with spring tang 'facing' the multi-connector, which needs to be placed back this way. Inserted, onto the spindle any other way round, will result in ignition key just rotating freely and doing nothing. The top cover is now added, a groove inside, now holds and secures  the spring resistance for key return on engine start, both elements are retained in place as the top and bottom cover's are then clicked into place, and secured.

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Rover 200/MG-ZR Technical and Information Pages (c) 2004-2018.

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