CE2 Tach wiring using W terminal in Caddy with AHU swap question - Upgrades (non engine related ) - VWDiesel.net The IDI, TDI, and mTDI source.

• CE2 Tach wiring using W terminal in Caddy with AHU swap question by estimatd on 15 Nov, 2013 00:12
• How's it going all?  Been a while since I've poked around here, hope all is well for everyone. 
  
  On a mission right now to get a legit tach working in my AHU swapped Caddy.  NGP did the swap and all the wiring some time ago, and to get a working tach, they took the mk3 tach signal and added a tach converter to work with a mk2 gasser cluster.  It works great but I just want something more diesel oriented with the correct redline.  So I got a MK2 TD ce2 cluster from Canadia that I want to hook up.  I swapped out the speedo to the VDO mph one and hooked it all up, but sure enough the signal for the tach is different.  I've done some searching around and I can't seem to find out how specifically to wire from a W terminal to a tach.  I'm hoping I can figure most of this out using http://www.a2resource.com/electrical/CE2cluster.html as a bit of a guide but I'm just not sure on the wiring from the W terminal.  Can I just run a wire from the W terminal directly to the tach pin out on the cluster harness? 
  
  I don't know much about wiring unfortunately (which was a huge reason for having NGP do the swap) so I'm hoping to find a bit of help.  I've searched around a bunch but haven't seen the exact info needed.
  
  Any help is appreciated, thanks!
  Charlie
• #1 by estimatd on 15 Nov, 2013 00:36
• So, sorry if this has been a subject relatively beaten to death, I just want to know how to wire it.  It looks like "Thezorn" answered the question in a thread here -> http://www.vwdiesel.net/forum/index.php?topic=31502.0
  
  From the sound of it, yes, I just have to run a wire from the W terminal directly to the appropriate pin in the cluster...right?
• #2 by CRSMP5 on 15 Nov, 2013 14:04
• 120a alt lacks w... has to be 90a.. or you have to mod the 120...
  
  also the calibration will be wrong too.. serp is different... so you will need to access the "pot" inside the tach to adjust it..
  
  feel free to ignore me on the 120a alt w if you wanna doubt me.. just telling ya.. tested/tried muliti and none work... its some type of engine load sensor for the comp..
• #3 by bbob203 on 15 Nov, 2013 14:11
• 120 has no W. End of story.
• #4 by estimatd on 15 Nov, 2013 17:26
• Ah, I see. I have no ac, no heat, no PS, it's really just a minimal setup, I wonder if 120 is necessary? If it is then I guess I better get soldering...
  
• #5 by bbob203 on 15 Nov, 2013 17:46
• I have a 90 amp in mine with headlight and heater running idle drops very slightly less than 50 rpm. I wish I could've used my 120 as I've heard these alts can't be opened without damaging them. Please make a how to if your decide to add a w to yours. you could probably just take and solder the wire that's on it where the w normally is to where a w would be soldered to to keep it plug in.
• #6 by CRSMP5 on 15 Nov, 2013 17:48
• na diesel bunny no ac = 55a... so the 90a serp one is direct fit.. just gotta recalibrate the tach.. aka adjust its pot.. what we did on bbob's...
  
  but if your 120a works... mod it... his was broken and we decided to put a 90a on it..
  
  my 90a in my kubvan.. the only times it hits 60 amps is when the base kicks on 1 song... the amp gauge dances.. with hid's it draws less amps (hell gauge barly moves).. but thats only 15 or so amp for h4s.. blower.. wipers... not even close...
• #7 by vanbcguy on 16 Nov, 2013 00:26
• Crazy, I was just going through Rock Auto today looking at alternators. There were 120A alternators available for the AAZ, and they are specifically listed as having "coupler for rev counter". There is a 120A alternator listed on my usual Canadian parts site too under the AAZ engine. Are they both wrong?
  
  I was looking at listing for a 1994 Jetta.
• #8 by CRSMP5 on 16 Nov, 2013 00:57
• i have seen 4 120a not have w.. actual hook up gauge.. on the tdi disconnected to see if tach worked.. and it did with the "w" not hooked up.. so what ever looks like 120 has w.. so far i cannot prove it does... but i bet it does not.. alt plug even has terminal that is hooked to a wire...
  
  2 90a that do.. but the 120 plug fits the 90 and vice versa... and plugged into a 90 works.. but 120 does not..
• #9 by bbob203 on 16 Nov, 2013 07:39
• The terminal on the 120 amp TDi alt that isn't the exciter wire is not a W. Its like a d+ or something.
• #10 by theman53 on 16 Nov, 2013 07:43
• Rabbit on roids had some 120 alt that had a W on it I think. Ask him what it was.