B230E ignition fault

[ROJ2]

Hi dave, thanks for your information, been away for a few days (on train) so sory for replying. Volts now on the 0261201009 module pin 6 ok & goes as you say to 0227100124 (found it!) unit (my misreading!). I gather a pulse comes from the distribulator to amplifier & then electronic switch (0227100124) to the coil, there seems to be many prices for this unit (if that is the fault) with same number (15015 alternative), do you know if they all fit the same & is there a way of testing the systems as it could be any of 3 units. Thanks for your input already & grateful of your knowlege of this model.
The fault started by needing 2 x batteries to start it & took a while but ok when running & warm but failed to fire completely after 2 days stood & has'nt worked since, thanks roj.

[Laird Scooby]

Originally Posted by Laird Scooby

This is pointing towards the ignition switch being the fault but further testing is needed. Locate terminal 15/+ on the coil (should also be fed with a BLue wire) and make a short lead to connect this directly to battery +ve - include a switch or make it easy to disconnect the lead from the battery quickly.

Connect this and try starting the car.

I'd give this a go before getting into the "what else" Roj - the fact it started with a booster battery sugests one of two things, first your battery is dead (despite spinning the engine over quite well) or the ignition switch is failing. This test eliminates the latter, or if the car starts provides another pointer to the igniton switch.

Not all 740 ignition switches are the same though so you can't just buy one on ebay or from a scrapyard and be guaranteed it works.

Originally Posted by ROJ2

I gather a pulse comes from the distribulator to amplifier & then electronic switch (0227100124) to the coil, there seems to be many prices for this unit (if that is the fault) with same number (15015 alternative),

Not necessarily. On some cars there is a sensor mounted in the top of the bell housing which provides this pulse. You need to inspect your distributor to see if it has the extra wiring into it for the sensor inside, if not the chances are it will be the sensor on top of the bellhousing.

The amplifier is what you're calling the electronic switch, what you're calling the amplifier is the ignition control module.

The ignition control module is the EZ-118K unit under the dashboard. This controls the vacuum and speed related advance curves (there should be a vacuum pipe going to it) and triggers the ignition amplifier module, on the inner wing behind the airbox.

Quick question - is your distributor mounted on the side of the engineblock towards the front or on the back end of the camshaft at the top rear of the engine?

[ROJ2]

Hi, the distributer is at the back (& looks awkward to remove) of the rocker cover, new battery has been fitted & yes there is a cable from the near side bottom of the distributer, thanks roj

[TonyS9]

Is the RPM needle flickering when you run the starter? (After 1s or so).

[Laird Scooby]

That sounds very like the older one, sometimes the cables that feed the sensor in the distributor can break but it wouldn't need an extra battery to get it to start under those circumstances. A million extra batteries wouldn't help it start if those sensor wires were broken.

However, if the ignition switch is failing as i suspect, it will drop some voltage across it. With just one battery, the voltage drop caused by the starter will be greater leaving for arguments sake, 9.5V available to run the ignition system.

If the igniton switch is dropping say 1.0V across it because it's going high resistance and the threshold for the igniton amp is 9.0V, with only 9.5V feeding the igniton switch and it dropping 1.0V across it, that would only leave 8.5V for the amplifier. As such it won't function.

Now add a second battery with jump leads - they are more capable of supplying the load the starter motor needs and while the starter is turning the engine over, because of the extra power supplied by the second battery, the voltage is still up at say 11.0V while cranking. That's 11.0V feeding the igniton switch which is still droping 1.0V across it but leaving 10.0V feeding the amplifier which is above the 9.0V it needs to operate. That means the car will start.

As you drove it around all day, the battery would be charged by the alternator, keeping the battery voltage up higher and the engine would be warmer resulting in an easier engine for the starter to turn. That means the battery is already more powerful to start with, the starter won't drop so much voltage as it's not working so hard so more voltage will get through the igniton switch to the amplifier.

These figures are typical from experience, not necessarily accurate for your vehicle and are used to explain the theory i'm basing my potential diagnosis on. It still needs you to test and prove/disprove my theory with the wire as described above.

[ROJ2]

Hi again Dave, you were spot on, I put a cable from battery to ignition coil & started straight away so switch must have resistance across it, so looks as if I have to get the right one for it, as you say they can vary, cheers roj.

[Laird Scooby]

Just to confirm that as the fault Roj, try it again tomorrow without the wire and it shouldn't start - fit the wire and it should. Removing the wire then probaly won't make any difference as explained in the long explanation.

Just to confuse us all, Volvo call them "starter switches", they can usually get all they need to find the correct one from the reg number.

To replace it, remove the steering column nacelle/cowl (3 or 4 screws from underneath, top and bottom halves clip together) and then find the starter switch on the back of the ignition barrel. It's fiddly but you can just about do it from there, you'll also need a small screwdriver, can't remember if it's flat or Pozi to remove the two screws holding the switch onto the ignition barrel, unplug the switch and remove.

Then "Haynes it" - refitting is the reverse of removal.

I think that's the correct method, it's a long time since i did the last one, i took photos but don't know if i can find them. If i can, i'll upload them for you and any differences to the method. Something in the back of my mind says i had to pop the instrument cluster out as well but can't remember exactly now.

Good luck with it, let us know how you get on!