Issues wiring to factory tachometer "LS Swap"

Ok I wired the P01 Green #10 wire to the tach signal wire on my 95 Volvo 940 and nothing happens on the tach. Drove by the shop this morning because I had a pack of resistors in my electrical cart, and did the resistor mod after I went to the junkyard and back. Spent some time ironing out a few other issues with the wiring and cooling system started it up and stuck the fuse in for my tach boost 12v source and nothing. After fooling around I stuck the fuse back in and watched the tach as I cranked the car over so the tach climbs upon startup to around 1700 rpm then nothing. I tried this 4 times, same thing. MY reasoning is that if I were to determine a certain ON/OFF pulse on the boosted signal it would work once set at the correct rate. I do not have a helper to watch the tach for me but I may try this tomorrow. Stick blades in and try to regulate the pulse with two jumper wires just to see if I am on to anything or not. There are signal translators out there but I am not going to jump the gun just yet. Any type of opinion or suggestion for a good device would be appreciated.

What resistor size and how did you wire it?

super hard to read the package... so, aside from the inventory part. MFG>Name: VISHAY BC COMPONENTS . DESC: Resistor Metal Film, 1330km, 400mK, 12% resistance 133ohms, Resistance tolerance+- 12; , Power rating400mK; Voltage rating 250v..... Oh that's a red flag right there, must have been some a/c component. there were 10 in the bag originally , light green with bands including .. large dark brown, black, two light brown bands and one thin dark brown all in that sequence. How I wired it was I ran pin #10 white from green plug to red/wht tach signal wire on existing gauge cluster and connected all 3 wires intersecting and sent the wire with the resistor to key on power at the fuse block. All of the power at this fuse block is key on only. I am sure it can be accomplished.

Going backwards through the bands you described, brown, orange, orange, black, ??? would be the band colors for 133 ohms. ??? for the last color because there is no color code for 12% tolerance. Could it be brown for 2% or gold for 5%?

At any rate, 133 ohms is possibly too low a resistance. Try a 1000 ohm, 1/4 watt resistor.

I think your wiring description is how it should be wired, but I'm not positive what you did. You connected the tach output from the ECM to the tachometer input wire. Then, connected the resistor between ignition power and the tachometer input wire? Right?

Yeah that's right, I am having trouble distinguishing the o from the zero on the package, I have another resistor and its a stray one. I will figure out what it is before I try that one. The one I have is a little larger , light green with sliver, red , purple and yellow bands. Don't really have any books on electrical components but can identify most of the time and make repairs on faulty components. maybe I can just check it with a meter. Either way it looks like I can obtain a boatload of 1k resistors for next to nothing, just have to order them.

The resistor above, referencing to a color code chart . Tolerance coefficient being gold or silver . this one has a silver band so the tolerance equals + or - 10 percent. with a yellow valued at 4 and a violet valued at 7 plus the red that represents the thousandths which equals 2 zeroes on the third band. this is a 4700 ohm resistor.

Did find a spare board that had 2 .68k resistors on it. de-soldered those and ran them in a series just as they were configured on the board. here's how I figured out what they were according to the bands. Looked at a chart. Big boys race our young girls but violet generally wins. that is the sequential color code from 1 to 10. there are more charts than that for tolerances, wattage ect... so anyways I soldered the two 680 ohm resistors together in a series and the tachometer on my 1995 Volvo 940 works like a swiss watch as far as the live data is concerned. That is 1360 oms or 1.36k .

hey, just wanted to drop by and let you know that i also LS swapped a volvo and used the same type of circuit to get the tach working. I used a 1k resistor and the tach normally works. Sometimes in the cold it gets "stuck" at the highest value and doesn't fall back down when the engine RPM decreases. I might play with the resistor value a bit and see if i can't get it to work right.