dec010974

iTrader: (1)

Hello ls1swap fam. I want to thank you for all ur help and assistance during my 5.3/4l60e swap. I have a concern in reference to wiring relays. I saw a relay position/photo, on another site, and it seems that the main battery power goes in to #87 of the relay. In my case, what worked for me was, #87 powers the accessories ie fan/fuel pump, once it receives the pcm signal/switch. The signal/switch is determined by #85 or #86, depending on the pcm signal. In my case, what worked for me is, #30 is connected to fused battery power. The relay switch moves from #87a to #87, when the pcm sends a signal to #85 or #86. These little questions/uncertainties can be the difference if ur swap starts/runs or not. any assistance with this helps. the answers will def. help others. thanks. keep on wrenchin'. also, we all love a good build thread.

Marky522

iTrader: (8)

Pin 30 is Battery power this is connected to 87a when the relay isnt energized, and connects to 87 when it is energized, not all relays have 87a. 85 and 86 dont matter as long as one is power and one is ground, they create a magnetic field which pulls the contact over to connect 30 to 87. Higher quality relays will also have a diode inside of them, that will save your PCM, when the control side of the relay loses power or ground the magnetic field collapses and induces voltage back into itself, the diode gives it a place to run out, it basically runs in a circle within the relay, instead of sending that spike back to the PCM, its just like the coil works on your engine.

HTH
Mark

dec010974

iTrader: (1)

thanks marky522 for the technical explanation. also, how do u know when ur relay has a diode? any how, as i did a lil research(net), my setup a running/driving swap, along with ur data proves correct. i even bought a stand alone(prewired) relay setup and wondered why it barely ran. as i cut and rewired the stand alone relay setup, in ran flawless. i guess a few harness makers dont know jack about how to wire relays correctly. i hope this helps all that may want to wire their own relays & create their own fuse blocks for ls1 harness'/swaps. thanks marky522 and ls1 fam.

#30 to fuse to battery.
#87 to acc. ie fuel pump/fan.
#85 to ground.
#86 to +12v.
note:pcm will determine which will be the signal/switch to power acc.

BelAir1000

iTrader: (1)

If you want to check for a diode, use a ohmeter and measure the resistance in both directions. One direction you should get a small finite resistance. The other should be an open load(i.e. infinite resistance).