For negative earth conversions the wire must be routed in the other direction undoing the knurled nut should allow the pickup to be dismantled and the wire reversed otherwise keeping the layout identical. I solder ground leads directly to the bulbholders as a permanent cure. Even headlights should only drop the battery voltage a couple of tenths, and cause virtually no volt-drop anywhere in the wiring or connections. Do you have enough power? Paul Hunt 2 Hi I guess I am not explaining myself clearly Paul. If you are looking for any different ideas for your own wiring diagram then this 78 mgb wiring diagram photo needs to be on the top of resource or you might use it for an optional thought. From the accessory brown wire is another smaller brown wire, this did run to the original alternator. Instructions are as follows: Purchase a diode 1N4005 from a local electronics store such as Radio Shack or Circuit City.
A single strand of wire will give perfectly good readings without load, but will drop to near zero under load. But I have checked those several times and all the wires come through the plastic electrical block and are the same color wire as they come out the other side. Mgb Distributor Wiring -- welcome to our site, this is images about mgb distributor wiring posted by Ella Brouillard in Mgb category on Mar 12, 2019. Not strictly part of this thread, but does anyone know why the relays are numbered as such. Lack of proper terminology I guess. The tach does not use a voltage stabilizer.
The headlights and driving lights alone use two to three times more power than the stock setup. I really appreciate the time you took to help me. Although inside our opinion, which weve offered the best mgb distributor wiring photo, but your opinion may be little different with us. Make sure pin 3 is connected to a good ground. Then follow with the Green circuit, from the W at the fuse box. I did the grounding test.
And possibly you have the tach signal and power reversed. The original instruments use the body ground by the wiper motor, and that should be the one to use, making sure it is sound, precisely because the dashboard 'ground' is not reliable and dependent on paint and physical fixings. I hooked one probe of the voltmeter to the battery + and one to the tach green wire and got a reading of. The Parts catalogue indicates these are 27H8215 for the 'Core', and 13H784 for the 'Loop-sleeve nylon '. Check V between this and Batt- should be less than. I removed the voltage stabilizer completely.
With as much load on as you can, you need to measure the voltages: 1. I thought that perhaps being tied into the same ground might be causing the problem. You should be able to get these down to 2 or 3 tenths of a volt each, but I have seen as much as 3v lost in one 'leg' and it still allowed cranking albeit slowly, and greatly dropped the voltage available for the ignition. The stock voltage stabilizer fluctuates between 0 and 12 volts, averaging about 10 volts. Take the alt to a shop and have it tested.
Is there an internal adjustment in the tach or is there a way to put a resistor in line to correct for what appears to be either an increased voltage or amperage or both ovet the old points system when the tach worked fine. I will send you comprehensive troubleshooting instructions, follow them first. However whether it is still cranking or not I don't know, neither do I know whether the battery is still any good or not. Also banged on about is the futility of looking for bad connections with no load on the circuits, all that will show you is a complete disconnection. Also you list several loads but do not indicate whether these were one at a time or progressively added.
The tach goes up and the speedometer drops as soon as I step on the brakes or turn the fan on. Am I missing something here? I re-wired the tach back to the green wire and ran another green wire from the tach over to the speedometer. Ray Ray 1977mgb This is all to do with bad connections throughout the system, from battery feeds on. The lights, , and brake lights are all on different circuits, so I don't think a relay will help. Make sure that wire from coil is on proper terminal. Paul Hunt 2 Thanks Guys It is back to the drawing board.
So the chances are the bad connection is at the solenoid. It was back up around 12. And I will post my results. Keywords for 78 Mgb Wiring Diagram :. Both would not make the dist. Make sure pin 3 is connected to a good ground.
Compare this to the nigh-on 2v lost between the battery and the green just with things like lights and fan, and you have a very bad connection indeed. If you can get good readings at the solenoid terminal, then disconnect all browN wires there and run a jumper to the coil+ and fuel pump W power for testing. On the main browN feeds, if this car not certain when this started has the flat plastic 4 way brown connector just behind the fusebox, it is a prime source of this problem. Or, is it anything to even worry about if the gauge stabilities after the engine starts? And we also believe it could possibly be the most popular vote in google vote or event in facebook share. The tach always had a direct green from 1967 on, before that it was a direct white unfused ignition. With a stock setup, only the temp and fuel guages are wired through the voltage stabilizer. We have been hunting for this image throughout net and it originate from trustworthy resource.