b3 passat wagon 16v to MTDI swap *Glow plug wiring time*

[theman53]

What if you added/continued the wire from the back of the gauge?

[CRSMP5]

google voltage divider...

each gauge think of as a resistor... sensor as a resistor...

if you draw this out.. it would be like a shape of a y.. gauges up top.. sensor at bottom... does it matter where you tap into the sensor signal? no matter how you draw it, think of it.. it will still be a Y

you have same issue with light up 2 position switches if your running a switch to share water/oil temps on the single gauge... key word light up switch.. non-light-up ones work great to change sensors... and with enough of those switches i gues you could share 1 sensor on 2 guges... but for what he needs a sensor for.. not needed.. no matter what the glow plugs will be on when not needed to be with a idi style glow plug set up...

[libbydiesel]

I wonder if you could use the alt exciter circuit as a switch.  Prior to the alt being excited, use the sensor to power the glow relay.  Afterward have it power the gauge.  Hmmm.

It's all academic, tho.  Easier just to tap the metal flange for another sensor...

[CRSMP5]

he could goto a non glowplug neck and solve it all... but he is worried on something that matters so little its not even worth this discussion..

i really do wonder how rover did their tdi m stuff before they went electric... and how the glow plugs work on their older idi vs the tdi...

honestly... a tdi will start in tempd a idi will not when their glow plug gives a issue... major differance in cold weather...

[bbob203]

he could goto a non glowplug neck and solve it all... but he is worried on something that matters so little its not even worth this discussion..

What? 

[libbydiesel]

I have used the mk2 relay.  I don't mind that it has the glow plugs run more than necessary.  This site and the Bentley both have the pinout.  I also have used the early aluminum coolant flange that had two sensors, one for glow plugs and one for the gauge.

[libbydiesel]

I think maybe what CRS was trying to say is that the coolant glow plugs are not worth the effort and installing an earlier neck with two sensors is the easy way.

[bbob203]

I was unaware that the older neck would fit i assumed it was different since the front is different.... I tossed the ones i had a few months ago it was pretty crusty though. Im sure i can scrounge one up.

[CRSMP5]

no.. i told you the old idi ones fit... back when we made the tap in the pipe for a sensor... but you wanted to wire in those glow plugs in the neck...

my worry libby is the harness for the glow plugs.. unlike a idi buss bar its got silly wires that fail... set off the check light..  and i know how warm a 8gauge wire gets with a single glow plug on it... aka testing them off batt to see if the work or not... the wire in a tdi  glow plug system seems under size to me.. the longer they stay on.. the hotter the wire will get.. and melt..

so thats why i have a issue with it...

[bbob203]

Wondering where I would plug in the wire to activate glow plug light. I have had no problem with the 10 guage wire on the glow plugs on my mk2.

[libbydiesel]

When I installed the ALH in my '91 Vanagon I installed the glow plug relay and most of the wiring but didn't finish the dash light or the actual harness to the glow plugs.  When I got my '02 Jetta Wagon, the PO gave me a new glow plug harness and told me that the DTC for glow plugs had be tripped and so he got the harness to swap in but hadn't gotten around to it.  I figured I'd install the new harness on the Jetta and install the old harness from the Jetta into the Vanagon using the mk2 glow plug relay.  Yesterday morning it was below freezing here and so the '91 had trouble starting without glow plugs and so I figured I should get to it.  I swapped the Jetta harness and finished the glow plug install on the '91 today.  The pinout for the glow plug relay is fairly simple and listed on this site in this thread.  The '91 has a couple of extra wires running front to back and I used one of those for the light.  I pulled apart the cluster and installed a radioshack yellow LED into one of the blank LED slots.  I had to install a 5K ohm resister on it, tho, to reduce it's brightness down to match the other idiot lights.  I spent a stupid amount of time trying to troubleshoot the system.  It turned out that BOTH of the NEW glow plug relays that I had on hand were not working properly!!  One of them did not function at all and the other one would trigger the glow plugs but not the instrument cluster LED.  After a considerable amount of time spent with the Bentley wiring diagrams and the multi-meter, I finally swapped in the relay from my '79 rabbit and it all worked as it should [bangs head on desk].  For wiring in the ALH glow plug harness, I just cut the four glow plug wires (14g) to the same length and did a crimp/solder/heat shrink connection on it to the relay.  The '79 relay is the slow glow relay and so I will update that to the fast plugs.  I was also thinking that I might do some resistance readings on the temp sensor and add a resistor to drop the temp a bit so the glow plugs come on less often and for a shorter duration as the TDI hardly needs them.     

[8v-of-fury]

so the glow plugs come on less often and for a shorter duration as the TDI hardly needs them.     

Been hovering around freezing all last week here too, glow plugs aren't even wired up on my M-TDI right now. Doesn't need them at all. Starts the same way at any temp this year so far. The two idi's in the driveway though.. need them indefinitely.

[bbob203]

Im thinking i will use 14ga wire them up in series? or individual? then to a single 50-60amp maxi fuse to push button activated starter solenoid.

[libbydiesel]

I'd feel better larger than 14g for individual glow plugs but that's what the ALH harness is.  I would not run them in series with 14g wire.  If making up the harness I would use 4 separate 12g or 10g wires.  I used (2)10g wires to run from starter lug to a 50 amp fusible link and then (2)10g wires from the other side of the link to the 30 terminal on the relay.  The momentary switch and starter solenoid is a fine way to go also, but i like to keep it simple for my wife.  "Wait for the yellow light to go out, then crank it over."

[8v-of-fury]

"Wait for the yellow light to go out, then crank it over."