Gauge Wiring Disaster - - Excellence in Motion
LinkBack Thread Tools Display Modes
post #1 of 1 (permalink) Old Aug 13th, 2010, 12:57 am Thread Starter
Join Date: May 2010
Location: Bellingham, WA, United States
Posts: 21
Gauge Wiring Disaster

I have an '87 K100 RS. I bought a BMW factory gauge and temperature sensor, but decided to build my own wiring harness.

Under the fuel tank, i found the optional gauge wiring connection -- its five wires, Grey/ blue, Green/ black (2X), Brown, and the yellow fuel level sender wire (not applicable for a coolant temp gauge). I removed the stock plastic connector and spliced one of the green/ black (power) wires, the brown (ground) and the grey/ black (gauge's light) into a new 4 pin connector that links to my temperature gauge. I installed my temp. sensor where my coolant drain plug had been, and ran its wire (black) as the 4th pin on my connector.

Brown went to brown, green went to green, grey went to grey, and black went to black. I double checked. My connections were insulated with high-temp electrical tape at every junction. As far as i could tell, all these connections were made good -- but something was wrong.

I turned the key, moved the ignition switch to on, saw the needle on the temp gauge jump to about 1/4 and stay there. tried starter:

nothing. no starter whatsoever. I think this is a clue, but i don't know why it happened.

then smoke -- the wiring i had introduced was melting.

I turned everything off and took it all apart (except the temp. sensor and wire to coolant drain plug... thats still on the bike). With the temp gauge uninstalled, the starter turned over and everything was back to normal.

Unfortunately (and perhaps very obviously) i know very little about automotive electrical systems. Maybe someone out there can guess what happened with the information i've already given, but i've taken some photos of the mess i've made, if not.

Of note is that the brown and green wires got the hottest: of the two, i would say that brown (ground) took the brunt of a lot of misplaced heat -- both at my fabricated 4 pin connector and at every splice i had made on the wires near it.

Why? There must be an obvious cause.

Also, the existing wiring harness under the tank has a "mysterious 'other' green wire" (noted in the photos) -- what is this? could i have confused the two?

Anyone recognize my mistake?
Attached Thumbnails
Click image for larger version

Name:	Coolant Gauge Wiring BIKE.jpg
Views:	31
Size:	137.3 KB
ID:	12454   Click image for larger version

Name:	Coolant Gauge Wiring GAUGE 2.jpg
Views:	26
Size:	181.7 KB
ID:	12455  
jlambert is offline  
Sponsored Links

Quick Reply

Register Now

In order to be able to post messages on the - Excellence in Motion forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:


Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode

Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuel gauge mwk12 K12/1300R/R-Sport 4 Jul 13th, 2012 3:49 pm
Installing a Coolant Temp Gauge on 1987 K100 jlambert Other K-Bikes Discussion 15 Aug 11th, 2010 11:59 pm
Looking for a Good Pressure Gauge XMagnaRider Bike Talk 8 May 22nd, 2008 4:40 pm
Temp gauge issue on my K100 Pro_Marinero Other K-Bikes Discussion 0 Mar 30th, 2008 4:55 pm
Wiring help please..... simply K1200RS/GT (Classic) 13 Mar 4th, 2006 10:53 am

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

For the best viewing experience please update your browser to Google Chrome