Starter and Load Reduction Relays

[FEP]

There is almost nothing that I can find on the forum (or in Bentley) about the load reduction relays or about what seems to be a starter system that engages the starter pinion before energising the starter. I am unable to diagnose what is happening with my starter (Pre-facelift 325i Sport but with facelift engine/loom) - can anyone (Brian) help?

One in 100 starts the motor would not turn although I believe that the dash lights did dim on turning to start. On these occasions the car would bump start easy enough.

This started to become more frequent particularly, I would say, when the weather was damp.

On other rare occasions, the starter would spin but the pinion not engage and even taking the key out of the ignition would not stop it. A whack of the starter with a large Maglight torch would stop it and the next try on the key it would generally start fine.

On one occasion that the starter would not spin, I tried connecting the two big pins on the motor with a claw hammer and sure enough the motor would spin, but the pinion would not engage - even with the ignition on and the starter key turned to start (clearly this required a dragooned passing member of the public to assist!)

Increasingly when the starter does work, it has become both lazy and prone to unusual noises.

I suspected a failing starter and failing solenoid.

Recently the failure rate has become much higher and today, with the starter refusing to turn and planning to bite the bullet and take it out, I discovered the ruse of connecting pins 11 and 14 in the diagnostic socket and to my surprise, started the car.

I'm now off to take a look at the Black/yellow wire from the ignition switch, but to be honest, I cannot figure the symptoms out - any ideas?

FEP

[Brianmoooore]

It may not turn out to be the only fault, but from what you say, it looks like a replacement starter motor is needed.
Face lift loom on pre facelift loom: Replace the small ring terminal on the black/green wire to the motor, replace it with a 8mm diameter one, and fit it to the inner large stud on the starter solenoid; the one that has a metal strap or thick braid going to the motor itself.
Connecting the alternator wire to this inner stud, instead of the outer one with the battery cable, can cause some of your problems, but if this was the case you'd also be asking why your battery isn't charging.

[FEP]

It may not turn out to be the only fault, but from what you say, it looks like a replacement starter motor is needed.
Face lift loom on pre facelift loom: Replace the small ring terminal on the black/green wire to the motor, replace it with a 8mm diameter one, and fit it to the inner large stud on the starter solenoid; the one that has a metal strap or thick braid going to the motor itself.
Connecting the alternator wire to this inner stud, instead of the outer one with the battery cable, can cause some of your problems, but if this was the case you'd also be asking why your battery isn't charging.

Thanks Brian.

As far as I recall, when I replaced the lump and the engine loom, the whole lot was post facelift - certainly I swapped my small diagnostics socket for a large round one.

However, the experience that I always seem to have of my wire colours being different to what the Zoners usually say continues. The wire on the top of the solenoid is Black/yellow (because Bentley says that this is the one from ignition I originally ignored the bottom one, which is thicker and black.) No sign of any green and the wire that goes to the ignition on the connector block on top of the steering column is Black/yellow. Very confusing.

The wire to the alternator is on the correct, outer, large stud.

Anyhoo, after fiddling around, at the moment, the starter turns when you turn the ignition switch. When I disconnect the Black/yellow (which attaches to a black wire) at the steering column connector, the starter does not turn. The ignition switch is providing 10.5v to that connector but only 7.5 at the solenoid. Removed the solenoid wire and Dremelled it shiny - still 7.5v only. When I earth the ignition end of the wire I have only about 1-2 ohms of resistance between the solenoid end and earth. This confuses me greatly. Where is my voltage going? Doesn't the solenoid need more than 7.5 volts to work reliably?

???

[FEP]

An update on this problem which I think I may have fixed.

After the problems last year, I acquired a new battery and the problem seemed to go away.

I considered that the low battery (we're talking maybe 11.9V) was the problem, but as when it does not start there is no solenoid 'click', I suspected the solenoid rather than the starter motor itself.

Recently the occasional no starter problem returned and now with a battery showing 12.5v.

I decide to pull the starter and learnt some stuff that I had not previously garnered from here/the Wiki/Bentley which may help others to know.

When the solenoid is energised it pulls a piston into a magnet which pulls an arm in the end of the starter motor which slides the drive pinion into position meshed with the flywheel. When the pinion is engaged, the contact on the starter motor is closed and the motor turns.

My solenoid/motor/pinion all seemed ok if a little dry. Testing showed that 11.5 volts would spin the starter motor and, separately, when applied to the solenoid, would fire the lever that pushes the pinion into position. I cleaned and re-greased everything and put it all back together, and so far - all is good.

What I think was happening was that the pinion slide and /or piston in magnet was sometimes sticking so that the pinion could not get into position meaning the the solenoid would not 'click' and the motor would not turn.

The thing that I still can't explain is the occasional spinning of the starter, without the pinion engaged, which would continue even if the ignition key was removed. Clearly the solenoid must have been sticking in the on position, but I don't see how the motor could fire without the pinion in position.

Sorry - forgot to take any pictures!

[FEP]

This starter problem continues to plague me. Perhaps 1 in 10 times when starting in the wet, nothing happens on turning the key to start.

I pulled the starter motor (again) and discovered that it is possible to bend back the whole circumference of the solenoid body where it is crimped to hold the connector block in place.

If I had been in less haste to get the bloody thing open, I might have noticed the lumps of solder on the 2 small terminals and done my self a favour by removing them. They hold the ends of the solenoid windings and if not removed, the wires break when you pull out the connector block requiring fiddly extending of the broken wire ends and re-soldering to the terminals after re-installing the block.

Having cleaned up the high-voltage connectors and copper connecting plate I re-assembled, re-soldered, re-crimped the solenoid body and tested the starter directly from the battery and it seems to work fine.

However, on re-installing the starter - IT DOES NOT WORK!!! GRRRRR.

This has taken me back to checking the wiring from the ignition switch.

First problem is that whilst Bentley shows 7 wires from the ignition switch I have 9. What should be black and yellow to the C200 connector is Black, but from there is a black/yellow wire which shows no resistance through to the 10mm connector that attaches to the starter.

I also cannot understand why the wire to the starter from the ignition switch shows 12v+ when the ignition is on, but WITHOUT turning the key to start. Turning to start boosts it from 12.10 to 12.5 volts.

I opened up the ignition switch, to clean, re-grease and re-assemble but I am quite unable to see how voltage is being delivered to the black/yellow wire without having to turn to start.

Perhaps more concerning is that with one end of the multimeter connected to the starter end of the black/yellow wire, whilst the ignition end shows no resistance, there is also continuity (with some resistance) at the ignition end of the violet and green wires at C200.

I have no idea where these wires go but I am assuming that they may go to S107 which is also where the black/yellow goes. Bentley says that S107 is 'beneath left side of instrument panel above glove compartment'. Does anyone know with a bit more precision where S107 is on a RHD 1987 pre-facelift 325i?

I am now assuming that whilst I have battery voltage at the solenoid wire, for some reason minimal current is getting through. Combined with the continuity with other wires, I am assuming that somewhere - maybe at S107, the wiring is a mess and shorting.

Any ideas? Am I going to have to take the dashboard out?

Could this have anything to do with the mess that is my door hinge panel connectors? I already have non functioning central locking even after having done the red/black wire mod to isolate the power loop into the door.

[Brianmoooore]

All the "oddities" you mention above are caused by back feeds from various things, and are normal. For most fault finding, a multimeter should be left on the shelf, where it can't cause confusion.
You say that 1 in 10 times nothing happens when you turn the key. Do you mean that if nothing happens, then it will start if you immediately try again, or that if nothing happens, then nothing will happen if you try again and again, but all will be good if you ome back the next day?
Assuming the S107 is the plug an socket BMW provided to connect the starter inhibitor on auto cars, then you'll find it behind the glove box area towards the top and to the right.
On the C200, the black/yellow (one side) and black (other side) wires aren't really part of the main plug and socket, and can sometimes not connect properly when the C200 halves are pushed together.
From what you've described, this all sounds like a simple intermittent ignition/starter switch, which can be bypassed, as a test, by linking the red and black/yellow with a short piece of wire at the C200.

[FEP]

Thanks for your indulgence Brian. I hate the fact that I have never properly got to grips with auto electrics so am very grateful for your guidance.

When its wet, the starter often works from cold, but after driving the car a bit, that is when the failure sometimes happens. Repeated attempts usually make no difference, but coming back later it will probably work. I couldn't say for sure that it has never failed in the dry.

You say that 'back feeds' are normal but I am testing the black/yellow wire for continuity whilst it is disconnected at both ends. That is why I am presuming that somewhere along the loom, there is a short with the other wires at the loom side of the C200. According to the Bentley wiring diagram, the black/yellow wire goes to S107 - a wiring harness splice location. Then again, I have always found that the wiring on my pre-facelift car never seems to quite match Bentley or diagrams on the Zone, which makes things even harder. My car is manual BTW.

I appreciate that the black to black/yellow connection at C200 is slightly separated from the plug, but the connection there appears to be good.

I am about to refit the starter motor. I will then be able to report whether connecting red to black/yellow at the C200 makes a difference, and indeed whether making the power connection at C101 does the trick. Assuming that my intermittent fault doesn't clear itself!

FEP

[FEP]

UPDATE

The starter motor is now fitted and all wires (correctly) connected.

1. Turn the ignition switch to START - nothing happens
2. Connecting red power in to C200 to Black/yellow starter out - nothing happens
3. Shorting terminals 11 and 14 on the diagnostics plug (not C101 as stated before) - car starts.

For 1. and 2. above, the ignition display lights noticeably dim a little when the connection is made.

[FEP]

First thing today the car started on the key. After driving for about 30 minutes, it would not start on the key. Then when I shorted pins 11 and 14 - IT WOULD NOT START. The shorting wire sparked a little and got hot.

I then shorted the black/yellow terminal at the starter with the battery in terminal and the car started straight away.

Is there a wiring diagram anywhere which shows the wires to/from the diagnostic plug?