Scooter70

iTrader: (1)

The car runs and gets hot but the electric fans don't come on. I have Flex-a-lite twin 12" fans, a Painless Wiring fan relay kit, and that's fed by the PCM thru the wires that Speartech put in the harness for me.

I think it's wired correctly but I should check it again. (John, to which relay pins should the two wires that were labeled "Primary Fan" go?) Where should I start troubleshooting? Connect the fans directly to 12V and make sure they spin? Then how do I check the relay? I don't have any type of scanner so I don't know what the PCM is reading for a temperature.

Once I get this cooling issue figured out, I can drive it further than just around the block.

Thanks,
Matt

Jones'n

Why don't they include the relays in the harness also instead of just adding some wires?
The computer supplies a ground signal to the relay coil. The other side of the coil should be 12V. See if those 2 wires check out okay, then start looking in to the fans and making sure they spin when they get 12V.
You might try just turning the key on and grounding the "Primary Fan" wire that goes to the relay from the ECM, see if that kicks them on.

Speartech

iTrader: (14)

Hook the pink to "86" and the green to "85". Make sure there are no other wires hooked to these terminals from the painless kit. They may have some ground wires hooked up as part of their kit and those must be removed to use the GM control setup.

That should do it.

Scooter70

iTrader: (1)

The fans spin when I give them 12V from the hot side of the relay. At what temp does the primary fan kick on? Maybe it's just not getting hot enough but my (probably innaccurate) gauge is reading 230*+ when I'm not moving. It does go down when I'm moving and getting air thru the radiator, so I know that the thermostat is opening.

Can I stick a voltmeter (or ohmmeter) on the LS1 water temp sensor and figure out what it is reading for a temp from that? Nobody in my area has stepped forward with scanning software on a laptop to help me read what the PCM is seeing. I don't like seeing the temp gauge pegged and I need to make sure that it really is reading high before I let the car idle to a temp higher than ~230*.

-Matt

Budman78

iTrader: (5)

Scooter
What temp sensor did you use? I decided to run my fans off of a Hayden stat that kicks on 200 and off at 185. It worked great with the old engine.
Oreillys rents scanners. The are autoX's so they should work. I guess I need to pick up a snap on scanner the next time I see one in the shops.

Speartech

iTrader: (14)

Did I program your PCM?? If so, I always lower the primary fan turn on temp down to around 210 for a stock thermostat.

If I didn't do your computer the factory turn on temp is 229! That could be well within the accuracy of your gauge reading. Let it run a little longer and see what happens.

You could run the engine up to a high indicated temperature, shut it off, unplug the sensor and measure the resistance. There is a resistance vs. temperature chart that you could use to get an idea of the temp, but it would be much easier to find someone with a scan tool and just read it direct while the engine is running. That would be the most accurate way to know the temperature is.

Scooter70

iTrader: (1)

Speartech: No, you didn't tune the PCM. It's still running on stock programming. Maybe it really is just not getting hot enough. Once I find someone to scan it and get the VIN, I'm going to order HPTuner and fix a few things including the fan turn on temp. I'll try running it hotter. How hot is too hot?

Budman: It's the Borg-Warner 510 (the so-called "Volvo" sensor on the other forum). Now that I think about it, I recall people saying that it read high. I know... you love the stock 78 sensor... but I believe that my gauge is different than yours and is expecting different readings. We don't have O'reilley's in Detroit. We do have Corvette Forum members who work at GM and have access to a Tech-2 though. Dave Decart is going to see if he can get the one from work today and I'm going to meet up with him tomorrow afternoon.

Speartech

iTrader: (14)

Let it go to 250 or so. I think your fan will come on prior to that and it won't be an issue, but even 250 or so won't hurt anything. The only way it would worry me would be if the coolant wasn't circulating, but you already have that covered.

Budman78

iTrader: (5)

Scooter, I used the one from a 82 vette. The 78 sensor was way to big. The ohm range was about 40 off. Temp difference is around 3 to 5 degrees.

I drove over to RPM in Lewisville today to watch them reflash and program some cars. They were using the Tech 2 by GM. To get it dyno tuned they want $475. I may scrap the dyno tuning until I do a head/cam swap. It was interesting as hell watching this guy go through the program adjusting timing and idle speed.