19 replies to this topic

[Lplus]

Presumably you've connected the + feed from the LG/O into the insulated spade connector on the tach (my memory failed there, it was the w/bk with the bullet connector.)

 

and presumably you found a screw to allow the earth to be connected to the hole where the screw was missing on the back of the tach.

 

If so it may be the tach is dead.

 

There should be 12v between the + feed and the w/bk female bullet as the w/bk leads to the - coil which is connected to the distributor which is not switching the current off to make a spark.  Or did you mean between the + feed and the male bullet connector on the tach?

 

The spare w/bk with the black insulator is probably the original connection to the distributor.  It is the other end of one of the w/bk wires connected to the coil -

[lippo]

 Thanks Lplus. Yes, the LGO goes to the spade, the neg earth from the small bolt/screw goes to the body and the bullet goes to the neg of the coil. The screw wasn't missing in the end, it was just in a slightly different position than some others I've seen. It screwed into the metal body f the tacho so I can assume it's the correct one.

 

The tacho was a bit beaten up when I got it, so it may have some damage.

 

I have been trying to test the tacho using this method but this doesn't seem to help either.

 

 

There should be 12v between the + feed and the w/bk female bullet as the w/bk leads to the - coil which is connected to the distributor which is not switching the current off to make a spark.  Or did you mean between the + feed and the male bullet connector on the tach?

 

 There's 12v at the female WB bullet connector which attaches to the male bullet on the tacho. You're saying that this is right which does then point to the tacho being knackered.

 

 I'll have another crack at this later on but will look for a new tacho too.

Edited by lippo, 31 May 2024 - 05:21 PM.

[Lplus]

 

 Thanks Lplus. Yes, the LGO goes to the spade, the neg earth from the small bolt/screw goes to the body and the bullet goes to the neg of the coil. The screw wasn't missing in the end, it was just in a slightly different position than some others I've seen. It screwed into the metal body f the tacho so I can assume it's the correct one.

 

The tacho was a bit beaten up when I got it, so it may have some damage.

 

I have been trying to test the tacho using this method but this doesn't seem to help either.

 

 

There should be 12v between the + feed and the w/bk female bullet as the w/bk leads to the - coil which is connected to the distributor which is not switching the current off to make a spark.  Or did you mean between the + feed and the male bullet connector on the tach?

 

 There's 12v at the female WB bullet connector which attaches to the male bullet on the tacho. You're saying that this is right which does then point to the tacho being knackered.

 

 I'll have another crack at this later on but will look for a new tacho too.

 

I'd use the correct location for the earth link to be absolutely sure, even though the screw you found seems to be into the body of the tacho.

 

The w/b wire should be +12v with the ignition on and the engine stopped, at least mine is, but that's a 65D electronic distributor though I don't see why it should be different for others.

[lippo]

I'd use the correct location for the earth link to be absolutely sure, even though the screw you found seems to be into the body of the tacho.

 

 

The w/b wire should be +12v with the ignition on and the engine stopped, at least mine is, but that's a 65D electronic distributor though I don't see why it should be different for others.

 

 

 I've swapped the screw to go into the hole that is the same as the PCB, took the coil off the mini and set up the test as shown in the link I posted above. This time, the car battery charger registered some interest. I looked at the needle and it barely lifted off zero but did vibrate slightly. I rechecked the connections and removed/replaced the screw to earth that I'd swapped, and now nothing. No recognition from the battery charger nor anything from the needle. I think the tacho is broken.

 

 I'll try again over the weekend. Thanks for your help Lplus.

[lippo]

 Did a bit more checking and used the advice from the forum and connected the tacho in the engine bay. + from solenoid, - from body and - coil direct from the coil - success! Tacho worked fine.

 

 I think it's the wiring in the dash that has been my issue. Tested the LGO wire and there was no feed when ignition in position 2. I found the white wire in the dash connector provides a switched feed so I'll use that. I'm just trialling the wiring to the tacho bulb illumination, that seem to be fine. Not sure whether to take the - earth from the PCB or link it to the mounting frame behind the dash. I've checked the continuity between the bullet connector in the dash and the - coil and it's good.

 

 Rain stopped play for now, hopefully I'll get it fitted over the weekend.