Dans toy Posted February 24, 2011 Share Posted February 24, 2011 I have a 2003 Lq4/Z project with a reworked stock harness that retains the high & low speed fan control wires (ground sources?) from the ECM. My Summit electic fan came with a relay that has large wire hookups & two small 16 gauge wires that activate the fan. One needs 12 volts fused & the other goes to a thermistat, which is a ground source. I would like the ECM to activate the fan but also have the ability to override with a switch. Can I run a switch supplying ground in parallel to the thermistat wire which I assume hooks up to the high or low speed ECM wires or would that damage the computor? Also does it make a difference what wire I use for a single fan(high or low from ECM)? Last question-If the ECM is getting the engine temp information from the sensor in the drivers side head, can I change it for aftermarket part to achieve a 180 degree activation temp ? Appreciate knowledgeable help. Quote Link to comment Share on other sites More sharing options...
SUNNY Z Posted February 25, 2011 Share Posted February 25, 2011 you might have better luck on ls1tech. There are a ton of fan questions over there. Also, TONS of great info regarding LSx engines. G'day Quote Link to comment Share on other sites More sharing options...
ColtGT4g63 Posted February 25, 2011 Share Posted February 25, 2011 I have a 2003 Lq4/Z project with a reworked stock harness that retains the high & low speed fan control wires (ground sources?) from the ECM. My Summit electic fan came with a relay that has large wire hookups & two small 16 gauge wires that activate the fan. One needs 12 volts fused & the other goes to a thermistat, which is a ground source. I would like the ECM to activate the fan but also have the ability to override with a switch. Can I run a switch supplying ground in parallel to the thermistat wire which I assume hooks up to the high or low speed ECM wires or would that damage the computor? Also does it make a difference what wire I use for a single fan(high or low from ECM)? Last question-If the ECM is getting the engine temp information from the sensor in the drivers side head, can I change it for aftermarket part to achieve a 180 degree activation temp ? Appreciate knowledgeable help. If you could post a wire diagram of the relay you are talking about, that would be great. You can run a ground switch in parallel with the trigger wire, shouldn't be a problem. Depending on which wire you choose to use for a ground trigger from the PCM, will cause the fan to trigger at different temperatures. The PCM is programed to have the low speed fan turn on at an earlier temp then the high speed fan. If you want it to turn on sooner, then hook it up to the low speed wire. I would not suggest changing the sensor just to make the fan turn on at a different temp. You'll effect other things by doing so. Like when the car goes into closed loop, fuel delivery, ect... If you really want to change things in the PCM like the fan functions, then you should get a tuning program like HPTuners and open up a world of options for yourself. Hope that helps. Quote Link to comment Share on other sites More sharing options...
Dans toy Posted February 25, 2011 Author Share Posted February 25, 2011 I have HP tuners. Just not very good with it. With a little help I did manage to find the ele. fan tables in "systems. which leads to other questions . The options are (2 fans) / (aux fans)/or (no fans) and if I choose "two fans" as I"m thinking I should, even though I only have one fan,which of the two pin out wires from the ECM do I choose (high or low speed wire as identified). The table options in the tuner are (fan stage 1) or (fan stage 2) . Each have an on/off setting & temp settings. Thanks for help. Dan Quote Link to comment Share on other sites More sharing options...
Ironman Posted February 25, 2011 Share Posted February 25, 2011 (edited) You can run a ground switch parallel, to both the PCM fan grounds. I more or less did the same thing, and everything works good so far. Granted my car doesn't fire up anymore, but that is because of other non related issues. I what I did was run a single speed fan, put in parallel the both PCM fan ground switches (Blue and Green), and then momentarily manually grounded the relay via a jumper wire. (To check if the fan works) The fan starts up and shuts off automatically when needed, no complaints. EDIT: For your application take the Summit themostat ground wire, PCM Fan Blue, PCM Fan Green, Your switch hooked up to ground. And solder everything together. Everything should work as expected. Edited February 25, 2011 by Ironman Quote Link to comment Share on other sites More sharing options...
Dans toy Posted February 25, 2011 Author Share Posted February 25, 2011 what do I gain by attach both the green & the blue together (I only have one fan). The table options using HP tuners are. 2fans/ auxfans/ or no fans. ? fan stage1 on,off fan stage2 on,off (both have temp settings which is understandable) How do these tables correspond with the options of using "low speed fan" or "high speed fan" wires from the ECM. thanks Quote Link to comment Share on other sites More sharing options...
Ironman Posted February 25, 2011 Share Posted February 25, 2011 When I had my PCM reprogrammed I left the 2 speed fan option on. I was originally using a Taurus 2 Speed Fan. Midway in the build, I changed to a single speed fan, Much simpler to wire. If you have the factory settings for fans wiring both the green and blue will activate your single speed fan for both LOW, and HIGH speeds. If you have the factory settings and connect only one color then, the fan will kick on during only the low OR the high speed temps. If you can modify Via HPtuners the fan parameters (Larger Temp range) and switch to a single speed fan parameter, Do that it is a little cleaner wiring wise. Since you are using one wire to control the fan turn on temp, I am assuming that you are running a single speed fan for everything. Quote Link to comment Share on other sites More sharing options...
Dans toy Posted February 26, 2011 Author Share Posted February 26, 2011 Thats correct. thanks for the help. Quote Link to comment Share on other sites More sharing options...
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