Testing the OD Solenoid

[Essex Stag]

About three weeks ago I posted about my OD had stopped working after it went in and out by itself several times . Most members pointed to electrical connections I have tested the circuit to the out going wire at the switch , crawled under the car and found the feed to the Solenoid loose and when touched it fell off Thought I had found the problem but No . Checked the earth from solenoid its OK. Is it just a matter of using a flying lead from the switch to the feed on the solenoid or is there any thing in between to test , the wiring diagram shows a connector between switch and solenoid but have not found that yet , as I am I only checking continuity am I right in saying I do not need to put it in gear or have ignition turned on . Only if I am checking voltage I would think I needed to do this. Is it possible to test a solenoid with out removing it from the car apart from driving it and finding it is not working . The oil level is OK

Derek

[Colonel Mustard]

Hi Derek,

There is another switch in the circuit. There is an isolator switch on the gear lever to prevent the overdrive from being engaged in anything other than 3rd and 4th gears (to prevent damage to the overdrive unit). You should be able to access it by removing the gear lever gaiter (just had a quick look in the repair manual rather than venturing out to the garage to check on my own car...getting lazy). I had the same problem with the overdrive on a Scimitar I used to own. I eventually bypassed the isolator switch because the Ford Zodiac switch was not easy to get hold of. I modified the wiring to prevent the overdrive from being engaged in reverse just in case I ever forgot to switch it off...but parts for Triumph's are far easier to obtain.

You could still have an electrical breakdown under load...which may not be detectable with a multimeter on continuity setting. If you can run a wire directly from the solenoid via a fuse and switch to a good live feed you will be able to confirm if the overdrive unit is working correctly or not. At least that way you will know which way to direct further diagnosis. Just make sure that you only switch it on when driving in 3rd or 4th gears as you will have bypassed the safety features (you must not engage overdrive in reverse under any circumstances).

Hopefully it is just a breakdown in a switch or connector.

Chris

[Lingen]

Derek. It might also be worth checking the connector between the wiring loom in the engine bay, and the gearbox loom. You will find it on the nearside of the engine bay, just above the chassis rail down by the pipe to the rear brakes. It gets very dirty down there, so I would pull it apart, and clean up the contacts with some sort of solvent. That cured the problem on mine some years ago. Mike.

[Firept]

Derek.
Agree with Mike check out that connector block. I find that paint brush cleaner is excellent for removing oil and grease muck, cotton ear buds also just fit the electrical sockets so that you can really clean them dont forget there is a fuse.
To test engage 3rd or 4th with ignition on engine not running you should hear the solenoid "clunk" as the gear leaver switch is operated you can also use the multimeter to check for volts feeding the solenoid.

Paul.