The solenoid on my 3.8S O/D sometimes doesn't actuate. It's more prevalent in hot weather and after a number of actuations. Say a lot of roundabouts on a dual carriageway (A27 Chichester is a good example).
Testing it with just the ignition on and in 4th the warning light comes on and the ammeter drops by a tiny amount I'd guess more than a single bulb) but no click. So I assume the circuit is ok.
Leave it for a bit and it works ok - once it's in it stays in (until I deselect then it may work again, it may not).
What could be causing this? Duff actuating coil on the solenoid or something else?
It did it last summer - I gave the wiring bullets a clean and it hasn't done it again until now. They're still clean and ok. So I suspect it's not that.
Is it possible to change the solenoid without dropping the gearbox?
Simon
Overdrive Solenoid Playing Up?
Moderators:Aceman, ecosselynx
Hello Simon,
I'm assuming an 'A' type overdrive. Yes it's possible, if a little fiddly to remove the solenoid. It's probably as well to remove the cover from the solenoid housing and remove and clean the armature if it needs it.
With the armature out of the way you can feel if the operating mechanism is free. (Although you can do the same on the opposite side with the setting arm.)
The solenoid has two windings, a pull in and a retaining winding, with the pull in winding being switched off by an internal switch (actuated by the armature being pulled fully in) in the base of the solenoid. It is worth checking this switch with a meter across the solenoid, you should see a higher resistance if you depress this switch. If not then it looks as though the switch or the winding is open circuit which could explain the erratic operation. The solenoid has an adjustment on it's armature and this needs setting sometimes, but if the overdrive does work occasionally this is probably OK.
Alec
I'm assuming an 'A' type overdrive. Yes it's possible, if a little fiddly to remove the solenoid. It's probably as well to remove the cover from the solenoid housing and remove and clean the armature if it needs it.
With the armature out of the way you can feel if the operating mechanism is free. (Although you can do the same on the opposite side with the setting arm.)
The solenoid has two windings, a pull in and a retaining winding, with the pull in winding being switched off by an internal switch (actuated by the armature being pulled fully in) in the base of the solenoid. It is worth checking this switch with a meter across the solenoid, you should see a higher resistance if you depress this switch. If not then it looks as though the switch or the winding is open circuit which could explain the erratic operation. The solenoid has an adjustment on it's armature and this needs setting sometimes, but if the overdrive does work occasionally this is probably OK.
Alec
Hi,
I had a similar problem, each time the overdrive deselected at the same point on the A1, aliens, martians? no poor connections and burning contacts on the switches.
I have no idea which overdrive I have as I bought and fitted a 'later' full synchro overdrive gearbox to fit in place of my non-over moss box.
Initially I found the short wire attached (only just) to the coil was only on a few strands (new one soldered on).
The second time it failed I used a multimeter on the switches and found the new switch on the gearbox top had a resistance. The easy solution was to fit a new switch and then wire this and the column switch to operate the low current side of a relay, leaving the main contacts of the relay to carry the heavier current of the coil.
So far so good after about 4 years (that should put the mocker on it now)
Brian
I had a similar problem, each time the overdrive deselected at the same point on the A1, aliens, martians? no poor connections and burning contacts on the switches.
I have no idea which overdrive I have as I bought and fitted a 'later' full synchro overdrive gearbox to fit in place of my non-over moss box.
Initially I found the short wire attached (only just) to the coil was only on a few strands (new one soldered on).
The second time it failed I used a multimeter on the switches and found the new switch on the gearbox top had a resistance. The easy solution was to fit a new switch and then wire this and the column switch to operate the low current side of a relay, leaving the main contacts of the relay to carry the heavier current of the coil.
So far so good after about 4 years (that should put the mocker on it now)
Brian
Hello Brian,
"The easy solution was to fit a new switch and then wire this and the column switch to operate the low current side of a relay, leaving the main contacts of the relay to carry the heavier current of the coil. "
It's essential for a long life of the switches for an 'A' type to be controlled by a relay, which is how they were factory fitted. 'J' types because of the much lighter current draw of the solenoid do not. There is no harm in having a relay with the latter however.
Alec
"The easy solution was to fit a new switch and then wire this and the column switch to operate the low current side of a relay, leaving the main contacts of the relay to carry the heavier current of the coil. "
It's essential for a long life of the switches for an 'A' type to be controlled by a relay, which is how they were factory fitted. 'J' types because of the much lighter current draw of the solenoid do not. There is no harm in having a relay with the latter however.
Alec
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