PDA

View Full Version : Sportster 1800 tachometer problem



dj211bfa
10-29-09, 03:27 AM
I have a 2000 Sportster 1800 with a 210hp Mercury M2 jet engine. I need help in fixing the tachometer! I already replaced it with a brand new one, thinking it was a bad gauge. I guess I was wrong! Obviously, it's something with the wiring or sensor on the engine. I checked wiring and fuse that goes into the tach gauge and everything looks good. The gauge powers up (needle goes up a little) when I turn on the key but just doesn't register the rpm while engine is running. There are only 3 wires that connects to the gauge however I don't know what each wire is for. I already know that the problem is not with the gauge but the connection to the engine or some type of sensor for it. Does anyone know how to fix this issue? I'd appreciate if someone can tell me a step-by-step proceedure on how to diagnose and solve my tachometer problem. Thanks! :coolgleam:

timmyboy76
10-29-09, 11:14 PM
if no response yet, pm him.

rookie101
10-30-09, 12:34 AM
Here's the break down of the wiring for the tach.

Purple Batery power

Black Ground

Grey Tach signal



The Gauge gets it's signal from the Grey lead coming from the Voltage Regulator/Rectifier. Do a continuity check from the ground wire on the back of the tach to engine ground and from the signal wire at the back of the tach to the Regulator/Rectifier to check for a broken wire.

Here are the OHM meter tests for the Reg/Rec



Diode Check: Connect NEGATIVE
() ohm lead to either YELLOW
lead. Connect POSITIVE (+) test
lead to thick RED lead.
100-400 ohms


Diode Check: Connect NEGATIVE
() ohm lead to thick RED lead.
Connect POSITIVE (+) ohm lead
to either YELLOW lead.
40K to infinity ohms


SCR Checks: Connect NEGATIVE
() ohm lead to either YELLOW
lead. Connect POSITIVE (+) ohm
lead to case ground.
10K to infinity ohms


Tachometer Circuit Check: Connect
NEGATIVE () ohm lead to
case ground. Connect POSITIVE
(+) ohm lead to GRAY lead.
10K to 30K ohms



Aaron:cheers:

dj211bfa
10-30-09, 09:40 PM
Can you tell me where exactly on the engine the Voltage Regulator/Rectifier is located at? There are a lot of wires and electric components on this Mercury M2 engine. It's very hard to trace the gray wire from the tach where it leads to. A pic will be nice if you have one available. Thanks for the help!

rookie101
10-31-09, 10:36 AM
Sorry no picture my Utopia has the Optimax in it. Your Regulator is located about in the middle of the engine on the starboard side near the ECM and the starter solenoid. Just look for a box with two yellow, two red and a gray wire coming out of it.

Aaron:cheers: