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Tachometer (rev counter) for Datsun B210.
Contents |
Overview
Datsun B210 tachometer (24855-H5100)
B210 box label says "24855-H6100 METER"
RHD vs LHD
The plastic box (housing) that contains the tacho is the opposite way around. i.e, a mirror image. The bottom tab is offset to one side. Apparently the gauge mechanism differs too since the wires are different.
when viewed from the front * LHD offset to the left of center * RHD offset to the right of centre
Right-Hand Drive
Left-Hand Drive
One-Wire vs Two-Wire
On a factory tachometer, the BW wire (Black wire with White stripe) is the signal wire. This wiring only matters if you wish to use the factory wiring harness.
- RHD tachometers use a induction-loop signal wire (two BW wire ends come out of the tacho) — like the B110 unit
- LHD tachs use a voltage sense wire (one BW wire) like most Datsun tachs starting in the mid-1970s
A one wire tach has ONE black/white wire not two (it also has the red wire and black wire that plug into the instrument circuit board ). I think all RHD 120Y wiring harnesses expect a two-wire tach ... Possibly you can adapt it either by soldering another black/white wire onto the tach (there is a spot), or just putting t-intersection in where the black/white wires connect on your wiring harness so that the tach is connected and the ignition circuit is still closed.
Two-wire RHD (two BW wires coming out of case)
One-wire LHD (single BW or BG wire coming out)
Wiring RHD
The tachometer is wired in series with the coil feed wire. There are two connectors that you pull apart behind the dash and plug the the tach wires into the loop, plus it has an IGN+ wire.
RHD Wiring discussion: POST 120y tacho trigger
Wiring LHD
The tachometer is wired to the coil negative terminal. All North America (and perhaps all LHD) B210s have the tachometer wiring right there in the dash. So no cutting needed, and no new wires need to be run out to the coil.
Early (BW wire) one-wire (single BW wire coming out). B wire is grounded to the metal case
EARLY USA bullet connectors * B ground (Black wire) * R IGN+ (Red wire) * BW signal (Black wire with White stripe)
Late (BG wire) one-wire (single BG wire coming out)
Used tachs may or may not come with the Tachometer Harness, which is used to plug into the Dash Harness. All B210s have the dash harness tach connector, even cars that didn't originally have a tachometer.
Rear three wires plug into mini-harness (all the red wires)
Tachometer Harness (mini-harness) * has two black Lamp sockets * has BW, B, R, RW and RB wires * 6-pin connector (connects to Dash Harness) one pin not connected * 3 bullet connectors to attach to Tachometer 1976-1978 with the 6-pin connector BW Coil- B Ground R IGN
1974 BW coil- B to terminal 'A' on dash R to terminal 'C' on dash
The signal wire is brought into the dash wiring even if it didn't come with a tachometer originally.
1974: signal is a single wire in the dash harness
1976: 6-pin connector in the dash harness
1976 CALIFORNIA: signal wire comes from the electronic ignition black
box (which is under the dash)
LHD
Tach-Volt Meter
Part Numbers
JPN 1973-1975
rectangle, 2-tab
(op.) S-all (exc. 4-GX), Van
24855-H5000 TACHOMETER
24860-H5000 TACHO. VOLT METER
S-all (exc. 4-GX), Van
25007-H5000 MASK-tachometer
round, 2-tab
24855-H5700 TACHOMETER GX
24855-H5500 TACHOMETER (op.) K-DX, K-GL
25007-H5500 MASK-tachometer K-DX
NORTH AMERICA 24855-H6200 ASSY-TACHOMETER OP -0775 [BW wire?] 24855-H7200 ASSY-TACHOMETER OP 0875- [BG wire?] 25007-H6100 MASK-TACHOMETER
Mask (delete blank/cover) 'DATSUN'
H51 B210GT [RHD GL 4-speed model] H61 LB210T [LHD 4-speed model] H62 LB210TRU A13 engine [LHD USA model (1974)] H72 B210 A12T [twin carb]