nazar Posted March 21, 2006 Share Posted March 21, 2006 As you guys know i got my lt1 running, the engine, and everything is fine, nice lopey idle, oil pressure, fuel pressure, etc.... I had lt1350 modify my harness it was a lifesaver ,BUT now I think I may have a slight problem. He wired in the fuel pump and cooling fan relays which is cool and they work. Fuel pump primes when ignition is on aand pumps when motor runs. When I program the ecu with the tunercat, and it reads the codes, the fan kicks on and off. Now when i flip the ignition switch, fuel pump primes, fans are off. As soon as i crank it and the motor starts, the fan kicks on and keeps runing. I am using a spal black magic fan, tons of air, but it stays on. What could this be? I dont run any emissions stuff, no air pump, no egr, no vats, etc... Also when I use a paper clip in the diagnostic port(top 2 pins) instead of t giving me flashing codes, it kicks the fans on as soon as i touch both, with the ignition switch on. Arent the fans suposed to stay off till it reaches a certain temp? I will get the tuner cat back and scan all the codes since my check engine light stays on, but was just wondering if any of you guys knew Quote Link to comment Share on other sites More sharing options...
Mr.INSANE Posted March 21, 2006 Share Posted March 21, 2006 Your fan maybe set up without a thermostat which could leave it on always when running. That isny neccesarily bad. Just keep an eye on your battery charge Quote Link to comment Share on other sites More sharing options...
nazar Posted March 21, 2006 Author Share Posted March 21, 2006 it should work lke a stock camaro, im using the stock ecu, stock wiring harness with the relays wired in by lt1350 Quote Link to comment Share on other sites More sharing options...
jbc3 Posted March 21, 2006 Share Posted March 21, 2006 You need to scan the computer to see if there are any codes set. If there are any codes, the fans will run all the time. I actually had the harness equipped with SES light wire. It also MUST be connected or the fans will run all the time. Other things like the speedometer (if you had a lead pulled from the computer) need to be connected also, or they'll set a code. I had my harness made up with both high and low fan relays and they work from the PCM signal just fine. When you program the computer w/ Tunercat or LT1-edit, they cycle the fan and fuel pump during the programming cycle. That is normal. I have never read the codes with a paperclip in the 4th gen f-body's (don't personally know if it works w/ these PCM's) I have always used either Diacom or Datamaster. Scan it and see, I suspect you have set a code somewhere. Jody Quote Link to comment Share on other sites More sharing options...
nazar Posted March 22, 2006 Author Share Posted March 22, 2006 i have the ses light wired in and it goes on like its suposed to and yes it stays on , i know i still have codes Here is my question, i specified the harness to have the ac, egr, evap, etc....stripped off and he left that stuff on. Will having that stuff not pluged in still throw codes? I think i turned most of them off using tunercat. And i wasnt aware of the leads not being pluged in throwing codes, that sux I dont have a speedo yet, aftermarket ones are $250 Also, another question, I have leads for oil pressure and water temp, can i hook those straight up to my stewart warner gauges? Or do i have to run seperate senders??? Quote Link to comment Share on other sites More sharing options...
Lewis Maudlin Posted March 22, 2006 Share Posted March 22, 2006 Your fan maybe set up without a thermostat which could leave it on always when running. That isny neccesarily bad. Just keep an eye on your battery charge If the fan was set up without a thermostat, it would come on when he turn the key to the run position and would not wait for the key to be turned to start. That was the way I had mine set up. Now, I have a Taurus fan set up with relays. Quote Link to comment Share on other sites More sharing options...
nazar Posted March 22, 2006 Author Share Posted March 22, 2006 its wired into the ecu, so the ecu controls it with its own thermostat Quote Link to comment Share on other sites More sharing options...
jbc3 Posted March 22, 2006 Share Posted March 22, 2006 The speedo not being connected is enough to set the codes to cause the fans to run. You may be able to put a resistor on the speedo lead to 12V to get the speedo code to clear until you get a speedo. (Call Dana and ask him) Scan for code when the car is running to see what issues you have before getting worried. Some of the connectors may be there but still jumped out. Jody Quote Link to comment Share on other sites More sharing options...
80LS1T Posted March 23, 2006 Share Posted March 23, 2006 Yeah your codes are whats keeping the fans on. You will need to turn off the A/C, Emissions, EGR, and whatever else your not plugging in to keep those from comming back. No you can't just wire up your sending units to the stock LT1 stuff, they wont read right unless they are set up the same way as the after market stuff(which they more than likely aren't). The oil sending unit is pretty much an on/off switch, all it needs is like 5 psi to keep your oil light from coming on. Your gauge needs more than on/off to work. Guy Quote Link to comment Share on other sites More sharing options...
nazar Posted March 23, 2006 Author Share Posted March 23, 2006 so why did he wire in the leads then for the water and oil? He put in seperate wires for those, along with the tach and speedo, and in his diagram its labeled as if going to the gauge...??I guess I'll call him tomorow and figure it out Got my driveshaft in today as well as my own fabed up front q45 mount, will be finishing that up tomorow. Still waiting to get the halfshafts Quote Link to comment Share on other sites More sharing options...
80LS1T Posted March 23, 2006 Share Posted March 23, 2006 You mean there are other wires/connectors besides the stock ones that are labeled "oil pressure" and "coolant temp"? Were do those wires go to(pcm?)? Guy Quote Link to comment Share on other sites More sharing options...
nazar Posted March 24, 2006 Author Share Posted March 24, 2006 they come out of the ecu, he wired in leads, its part of the package that he does to the stock harness Quote Link to comment Share on other sites More sharing options...
jbc3 Posted March 24, 2006 Share Posted March 24, 2006 Since I used the stock 280 gauges, I did not use the leads that were in the LT1-350 harness. Those outputs will work with stock Chevy or Autometer gauges. I ended up using the stock 280 harness leads for both temp and oil pressure and installed 280 sensors in the LT1 block. Neither of these set codes because they were not connected. Jody Quote Link to comment Share on other sites More sharing options...
wheelman Posted March 24, 2006 Share Posted March 24, 2006 jbc3, You've said a number of times in this thread that not having a speedo connected will throw a code. Where are you getting this info? I ran my car all last summer using the Datsun mechanical speedo and had no codes generated. I did have to simulate the SES light but once that was done all codes were eliminated. Wheelman Quote Link to comment Share on other sites More sharing options...
80LS1T Posted March 24, 2006 Share Posted March 24, 2006 I did not know that you can use Autometer gauges with the LT1 oil pressure sending unit? I was told its pretty much a switch, on or off? I thought the Autometer sending units were basically variable resistors and thats how the gauge knows what to read. If you can use those leads coming out of the PCM then just hook them up to the gauges and see what happens. Having the speedo code though might still make your fans run all the time. Once you get everything hooked up and working then worry about the fans. Guy Quote Link to comment Share on other sites More sharing options...
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