QuestionQUESTION: In the course of rebuilding our 78 MGB we decided to install a new main harness. All is well except we have a total of 6 leads/connectors coming from the new harness not accounted for.All are under the dash. There is a double GPK, a single GPK double WR and a single G grouped near the right hand defrost tube.We believe these are all for a Service interval counter and light which our car apparently never had.Can we leave them dead ended?
We have a pair of singles GPur and Purpk, if I remember correctly at the very end of the harness, left of the steering wheel,that appear to be for a door buzzer module, which again our car doesn't seem to have had.Does any one still sell this module?
Lastly there is no specific feed on the harness for the radio, normally WG. Can we safely pick up a feed from an available Green
Thanx
ANSWER: Hi Fergus,
You need a wiring diagram to sort that out. I will try something new, go to my website and see if you can download the "diagram" and "index to the diagram" from this URL.
http://mg-tri-jag.net/DownloadPage.htm
Download the diagram and the index by right clicking it and then left click "Save As" so you can place it anywhere on your PC that you want and then print it. Do the "index to the diagram" the same way and then let me know if it came out ok.
Compare the diagram to your new harness and see if it answers your questions. Let me know,
Howard
---------- FOLLOW-UP ----------
QUESTION: Thanks for the quick answer. Your wiring diagram seems to be the same as the Haynes diagram we are using.It shows the Service Interval Counter Item 12 and related items at the bottom right in dotted lines. There was no such device in our car.Can we leave the harness wires as is, or do they need to be interconnected in some way. What does the diode look like? Where do you find it?, Is it essential to any thing?
Yes or no can we use a spare green feed from a connector under the dash for the radio, as there is no correct white and geeen feed connector coming from the harness.
Thanx again
AnswerI believe the Service Interval unit was just a warning light as I remember. As long as you don't let the wires short out You should be ok with them as is. I have looked through everything I have and I can't find the location of the diode either and I don't remember ever replacing any when I worked in several MG dealerships. The only thing I remember being said by BLM when they added diodes was that they did it because of a back feed of current to the ignition when it was turned off. As you can see in the diagram, you can just take a volt meter and connect the leads of the volt meter up at each end while using the ohms test and then reverse the leads to see if the diode is built in to the new harness.
Lucas wiring uses green wires to operate accessories, so as long as you test the wire to see that it is only hot when the key is in the run position and the green wire does not have a colored tracer on it. Then you should be safe using it for a radio as long as the radio is not a high amp for large speakers. Most green wires are only 14 ga. so they can be used for most accessories like a radio. Be sure you either connect the case or a ground wire to any black wire or clean body connection for a ground.
Let me know how it progresses,
Howard
