M:\Product Information\366-348\Instructions\366-348 MGB Fuel Injection Installation Instructions_Grant_2.doc
Installation Part 9- Tapping into the Tachometer Wire
108.
If you have a “Federal” MGB (built for sale outside
California) you should have a cylindrical barrel-type coil
(60.1). Locate the two white w/black stripe wires
attached to the negative side of the coil (60.2). Look at
the coil; the negative side of the coil should be marked
with a “-“. One white w/black stripe wire goes to the
distributor and the other goes to the tachometer. Both
disappear into the wiring harness so it is hard to tell
which is which.
366-348 Inst Fig 60, Federal MGB
60.1
60.2
109.
If you have a “California” MGB you may still have
the electronic ignition coil fitted that was part of the
emissions control equipment (61.1). Find the two white
w/black stripe wires (61.2) attached to the coil.
61.1
110.
In either case, once you have located the two white
w/black stripe wires, try to determine which of the wires
runs to the tachometer. This may prove a challenge.
Although we can tap into either wire, it is best to use the
tachometer wire.
61.2
366-348 Inst Fig 61 1979 California MGB
111.
Find the T-Taps supplied in the kit (Fig 62).
One
the cars with a regular coil, you could put a #8 ring
connector on the white wire and secure it to the negative
terminal on the coil. On the cars with the electronic
ignition coil, the wires disappear into the coil and you
cannot do that- which is why we supply a t-tap in the kit.
366-348 Inst
Fig 62
63.1
366-348 Inst Fig 63
112.
Place a T-tap on the white wire with a black stripe
(white-black) that goes to the tachometer. (63.1) (Again,
either wire will work).
This connection will provide a tachometer/RPM signal to the ECU while allowing the tachometer
and distributor to continue to work normally. Note: If the wires are old, squeezing the T-tap may
force the blade into the insulation without actually penetrating to the wire strands inside the
insulation. After installing the T-tap, use an OHM meter to verify continuity between the female
spade in the T-tap and white-black wire. On the Federal cars, check continuity to the negative
terminal on the coil. On the California cars there is no visible negative terminal because the white-
black wire disappears inside the coil. You will need to penetrate the wire with a sharp probe.
This completes part 9 of the installation.
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