Alternator Problem? Mira L200S engine

mouse8899

Known Member
Oct 28, 2012
76
12
508
petaling jaya
Any sifus here willing to help?

Engine is a Mira L200S. Bought a new battery and crank it up. Response on the engine is slow and not revving fast enough. Multimeter reading is around 11-12+ volts.

Revved the engine and the reading stays at 11-12+ volts also. But when I disconnect the battery or the socket at the alternator, either one, the engine revs normally. What I can see here is there is only output for the battery and no input. When I connect the socket/battery back again, the engine idles very low. Positive battery cable gets very hot too.

Any help will be much appreciated.
 

nyantong

Known Member
Senior Member
Jul 26, 2008
192
50
1,528
Usually the alternator should have a reading of 13+ volts when revved. Its quite possible the alternator needs to be overhauled. But you should also check the alternator cable's resistance to make sure its the alternator thats kaput and not the cable
 

Supra_Fanatics

Beyond 20,000 RPM!
Senior Member
Sep 17, 2008
20,673
3,998
1,713
Does it matters or will it work if use a fake grounding cables? Like not the ori type?
 

vr2turbo

Beyond 20,000 RPM!
Helmet Clan
Moderator
May 11, 2010
29,998
8,385
1,713
Petaling Jaya
Does it matters or will it work if use a fake grounding cables? Like not the ori type?
Fake in this situation, probably will not damage anything, except for it being of poorer quality, therefore not getting the full potential of the grounding cables....
 

mouse8899

Known Member
Thread starter
Oct 28, 2012
76
12
508
petaling jaya
before change battery also same, no charging. today swapped in a working alternator from my friend, there is charge but no the normal reading. grounding terminal should be okay, was using jumper wires.

previously - 11-12+v
good alt - 12-13+v (revving hard)
normal reading - 13-14+v

very suspicious reading so went and splice open wire harness alt>bat/ecu, found the single big wire insulation melted. possible cause of wiring shortage that's draining the power. gonna replace the wire tomorrow and see what happens. hopefully that is the cause... if not i don't know what to say.

will keep you guys posted on updates and thanks for suggestions/help
 

vr2turbo

Beyond 20,000 RPM!
Helmet Clan
Moderator
May 11, 2010
29,998
8,385
1,713
Petaling Jaya
Oh! wanted to post that something is wrong with your wiring, because the rev drops after hooking the terminal back on, that is why I ask symptoms before battery change, to rule out the battery first. Looks likely that is the problem.
Let us know and if possible some pics of the damaged wire.....
 

mouse8899

Known Member
Thread starter
Oct 28, 2012
76
12
508
petaling jaya
yup, confirmed the main culprit was the big fat wire. :proud:
replaced wire now with normal engine response, but alternator still need to service.
will upload the damaged wire image by tomorrow

by the way, is there anyone that know of L200S ECU pin-out? was trying to find the tach signal that was taking forever... or can mount the tach signal wire to the 1 cyl on the distributor cap contact point?
 
Last edited:

Random Post Every 5 Minutes

Hi Guys,

Any recommendation on how to DIY to protect your head lamps from turning yellowish over time?

Thank you.
Ask a question, start a discussion or post something for sale!
Post thread

Online now

Enjoying Zerotohundred?

Log-in for an ad-less experience