Electric fan control confusion

[NC_John]

I am having the strangest problem with the control of my electric fans and unfortunately I am the best controls guy I know so I don't have anyone that can come over and look at this.

Lsx swap.
Speartech harness.

I've got two pair of wires coming from the speartech harness to control my fans (primary and secondary). I have each of these signal pairs wired to bosch relays on pins 85 and 86 (coil terminals) (this is also as speartech instructs). I have 12 v (constant) directly from the battery wired to terminal 30 on the relay. Power to the fan is from 87 (the normally open side of the relay). Pretty basic stuff.

Here's whats got me beating my head against the wall.

The fans simply won't come on.

When the engine reaches temp (don't recall the setpoint we put in hptuners), i am reading 12 vdc across the wires coming from the harness using my fluke multimeter- so the pcm is indeed calling for the fans to come on. BUT it won't trip the relay when connected. When I measure the 12vdc from the signal pair and then plug in the relay it doesnt trip.

I tested the relay and can trip it using jumpers to the relay with power directly from the battery. Its a decent "click," meaning the relay seems healthy. I also checked resistance across 30 and 87 with an ohmmeter when I cycle the relay and it works fine. I can engage the fan when I jump 30 and 87 (bypassing th relay). So everything logic-wise seems correct. I have confirmed the terminal positions on the relay and the relay harness. They are correct.

I had everything soldered and heat shrunk but i thought the problem could have been in the relay harness so I reluctantly cut my connections and put new crimpons on the four wires, thus bypassing the relay harness and its connections. Didn't help.

I am wondering if the signal from the pcm just doesn't have the nuts to trip the relay but that doesnt make a lot of sense. Speartech instructs to wire each of their pairs of control wiring so it must be strong enough of a voltage signal. I even tried to measure the current but couldnt get a reading with my meter. I'm using a bosch 0332209150 relay 12V/20/30A.

The only thing left I can think to try is to buy another brand relay and see if the pcm can trip it.

Ideas? Anyone?