7427 Efan

[CDeeZ]

After googling around for 7427 E fan control I found this:

http://www.fullsizechevy.com/forum/general-discussion/performance/tbi-tuning-87-95-obd-i-ecm-pcm/446107-new-electric-fan-code-0d.html

When I try to copy the code into hex editor tool in TPRT it doesn't copy right? Does this have to be entered manually?

[EagleMark]

The zip file from 93V8S10 with all info is here:
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?303-16197427-PCM-Information-OD&p=3536&viewfull=1#post3536

The conversation is here:
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?468-Another-option-for-0D-efan-control

It is for $0D... I'm sure it could be implemented to $0E but not sure anyone has yet...

[CDeeZ]

Thanks. How come when I try to copy the code at the bottom into the hex editor it pastes all wrong?

[EagleMark]

:confused:

[Six_Shooter]

Have to enter it manually, copy and paste doesn't seem to work in hex editor.

It doesn't take long, I think it took me less than 5 minutes to complete all of the changes.

[RobertISaar]

with the new patch item in tunerpro, it can now be done almost automatically.

[CDeeZ]

I found a free hex editor on the net last night. I was able to copy and paste it just fine using that hex editor. Open the new bin in TunerPro and it appears as if the efan code was installed properly.

Robert, how do you use the patch feature in TP to apply this, just curious?

Here is the free hex editor I found if anyone else wants it!

[RobertISaar]

it works pretty simply, just add in the areas of the BIN that are patched, what they get patched to, what they were originally(if you want to be able to revert it back to unpatched) and you're pretty much done. works awesome.

[CDeeZ]

When I go to patch in TP it wants to open up an 'Srecord', what do you do there?

[RobertISaar]

that's the old way of doing it, which i've never gotten to work...

this kind adds it to the XDF, try making a new item (scalar/table/etc) and you'll see patch as an option(if you're running the newest version).

[CDeeZ]

Thanks Robert,

I'm going to try that method next time I boot into the Windoze side of my HDD and have access to TPRT.

Did anybody check out that hexeditor I found? Pretty neat I thought. I was easily able to open the bin, copy the Efan code into the appropriate addresses in the hex, and save a new binary!

[EagleMark]

Did you know TunerPro has a built in Hex editor? Tools, advanced, hex...

[CDeeZ]

Yes, I know TunerPro has a built in hex editor.

But like I said, I couldn't get it to work for copying and pasting the code itself into the proper addresses in the binary.

I typed it all in manually in the hex editor in TP, then went to close the hex editor, then I got: "Bin modified, Save?" clicked yes, and somehow, miraculously, it didn't save?


The point of the program I shared was that you can copy and paste the code into the hex thereby saving time. Not to mention the possibility of messing up something while transcribing the code manually one character at a time.

I could have probably spent another five minutes manually entering the code into the hex editor in TP, a second time, but doing it this way is so much easier and faster :rockon:

[EagleMark]

Thanks for sharing the hex editor!

Although I try very hard not to use them, great for checking a paremeter just made though. Just me... I use the Hex all the time to find mask ID, but other then that? it's like VooDoo... :laugh: I've got a lot or respect for guys that used to tune cars via hex! :thumbsup:

[CDeeZ]

I wired up the fan to the PCM but it won't work. Followed directions exactly as prescribed in the included document file with the patch. I set the fan enable temp low to like 40 F to test if the PCM would command the fan on but it doesn't!

[CDeeZ]

Does anybody have any ideas? I recall finding a post by 93V8S10 where he talked about some of the '7427 PCMs used in HD applications had pin E3 setup differently, therefore the efan code might not work on those PCMs found in the HD applications? I can't seem to find that post at the moment.

For testing purposes, I have "Temperature for fan on" set to 80.2 and "Temperature for fan off" set to 304, this should make the PCM command the fan on all the time since ambient air temp is currently well above 80 degrees correct? Or am I doing that backwards? I'm just trying to set the fan low enough so I can test it in the driveway w/o even warming up the engine

I'm going to try the other 7427 PCM I have and maybe see about the pin difference on E3 that I recall 93V8S10 talking about.

Also, When I wiggle the wire I pinned to E3 for the E-fan, I can hear something clicking under the hood, (possibly a relay) and then the vehicle dies. I used ONE 50amp relay as I thought that would be better than stacking two 30amp relays. It is my understanding that having two 30A relays wired parallel does NOT give you the equivalent of a 60amp relay, probably more like 45amps I'd think?, and even then, during fan startup I believe there would be a moment, however slight, when the entire electrical load is going through just ONE of the 30A relays.

[RobertISaar]

you need to correct those fan settings....

think of it this way:

when the temp rises above the on-point (80*F), it wants to turn the fan on. then when the fan is on, it will turn it off once under the off-point(304*F).

can you see why it won't turn on? the off-point needs to be lower than the on-point, technical term is a hysteresis, it allows what is essentially a window of on or off operation.

also, all 7427 should the same internally, otherwise they would have a different part number.

and 2 30 amp relays WILL act similar to a 60 amp relay, assuming they are both connected well(properly sized wires, good grounding, etc), just they will have twice the current draw for the relay coil, which will be ~1/3 of an amp with 2 relays.

[CDeeZ]

Thanks for clarifying that.

I set fan on to 70.7 and fan off to 69.4 to try and force fan on to test it but it still doesn't work. Any idea what I'm doing wrong?

Maybe somebody could take a look at the bin I posted the see if in fact I got the patch applied.

[CDeeZ]

Ok I just realized something that might be my problem. The included .doc with the fan code for $OD has something at the very bottom for wiring directions. This is what I've been using, but I see now that this is talking about the special solid state relay that 93V8S10 used!! I just have an off the shelf 50A relay for "coolant fans" that I got from Napa, and it shouldn't be solid state. Looking all over the internet I find all kinds of different ways to wire relays for Efans. Can anyone tell me how they wired up their fans with just standard relay(s)?

Or more specifically, how do I wire this up on the 427 with out solid relays

[RobertISaar]

same as you would with a solid-state relay....

the PCM controls the negative side of the coil(or "coil" in the case of the SSRs), so you give it +12V on the other side of the coil.

on the load portion, just interrupt the main +12V feed to the fan(s) with the relay.

[CDeeZ]

Here's how I have it wired as of now:

30= BATT +
85= PCM PIN E3
86= BATT +
87= FAN

This IS different from the way the wiring is listed in the .doc included with the efan control patch for the 7427
Pin 85 is listed as Ground high amperage and Pin 86 is to PCM.



With the relay wired the first way I listed, I got the fan to come on instantly with startup with the enable and disable temps set to 70.7 and 60.4 respectively.

I then burned another chip with the temp on set to 284 and temp off set to 282.7 and the fan didn't come on (cold/warm started in driveway on both tests)

[CDeeZ]

After testing the efan in the driveway I burned a chip with the fan set to turn ON @ 204.4 and OFF @ 203. Went driving around town and saw temp starting to come up to the 204 mark so I hopped out, popped the hood and in no time at all, POOF! the fan magically turned itself on :)

I love it when stuff works and/or I can figure it out.

I'm planning on leaving the wires alone since it works this way, I just have to add inline fuses to the two wires going to the + BATT post, since I temporarily have them hooked up w/o fuses

I noticed that 93V8S10 had his fan set to turn on at 10 degrees ABOVE the temperature his thermosta opens (160F) Is there any reason for this? I copied what he did in that sense, my thermostat is 195F and fan ON is 204.4F, roughly 10 degrees difference.

Also, in the included document with the fan code, the section at the end talking about relays and how to wire them is a bit confusing I think... I hooked it up exactly as stated and it didn't work for me until I tried something else.. I really think we should revise this document to eliminate the confusion, uncertainty, and wrong information that I experienced. I'd be happy to do a quick ninja edit and tighten up these directions, possibly even expound a little bit on how and why to wire it a certain way?

[RobertISaar]

i was gonna say, based on your last post, it sounded like it was functioning exactly as intended...

anyways, 10-15*F above the stat rating is what i do as well, depending on how sticky it is. a lot less thermal cycling that way.

[EagleMark]

I noticed that 93V8S10 had his fan set to turn on at 10 degrees ABOVE the temperature his thermosta opens (160F) Is there any reason for this? I copied what he did in that sense, my thermostat is 195F and fan ON is 204.4F, roughly 10 degrees difference.

Also, in the included document with the fan code, the section at the end talking about relays and how to wire them is a bit confusing I think... I hooked it up exactly as stated and it didn't work for me until I tried something else.. I really think we should revise this document to eliminate the confusion, uncertainty, and wrong information that I experienced. I'd be happy to do a quick ninja edit and tighten up these directions, possibly even expound a little bit on how and why to wire it a certain way?I'm sure 93V8S10 would appreciate any feedback and helpful hints to all the work he has done. I know I found one thing off a little when using his work and mentioned it to him and he was very apprecative.

[CDeeZ]

i was gonna say, based on your last post, it sounded like it was functioning exactly as intended...

anyways, 10-15*F above the stat rating is what i do as well, depending on how sticky it is. a lot less thermal cycling that way.

Awesome


I'm sure 93V8S10 would appreciate any feedback and helpful hints to all the work he has done. I know I found one thing off a little when using his work and mentioned it to him and he was very apprecative.

He's on this forum isn't he? What is the best way to get in touch with him? I certainly don't intend to complain as I am very appreciative of the work he's done! Just want to help!





Thanks guys

[CDeeZ]

I'm going to pick up some inline fuse holders on the way back home today to complete the install. What size fuses should I use for each of the two wires going to the + battery post?

[RobertISaar]

depends on the fan....

with a lot of the GM factory stuff, expect something along the lines of a 40-60 amp maxi-fuse per fan. it only really needs that much overhead when starting to spool up, otherwise you could get away with a 20 amp fuse.

[CDeeZ]

I'm not sure exactly what the fan is from as I bought it from a friend several years ago. I believe it came out of like a 2001 cadillac of some sort.

I'll get a fuse holder and several fuses in the 40-60A range and see how low I can go on the fuse without it blowing..

And on the fuse for the +12v to energize one side of the relay armature, that I can get away with a 5A fuse surely?

[RobertISaar]

the relay coil draws something like 1/6 of an amp everytime i've put my multimeter to them, so yes, 5 amps should be fine, getting fuses under that is iffy at times, so i'd stick with a common value like 5.

if you could find a part number on the fan, it might be possible to look up what it came from, in which case i could probably look up the wiring diagram for it's original application.

as an example: 2001 cadillac eldorado, both fans are connected to the same 50 amp fuse. it works a little bit differently than yours will, since that application starts both fans off at low speed and if necessary kicks them both on to high speed, so it avoids the large current draw necessary to start at high speed from a dead stop.

[CDeeZ]

Ok 5A it is for the relay coil.

I'll see if I can find a p/n on the fan.

The fan I have is a single fan, so maybe it didn't come out of what I thought?

It has what looks like some ballst resistor on it, but it's not connected and I'm not entirely sure that's what it even is?

[RobertISaar]

really big resistor? probably used for dual speed operation. i haven't seen many GMs with that, but fords i've seen with them.

[PJG1173]

just a fyi this is how I wired mine up http://www.gearhead-efi.com/Fuel-Injection/showthread.php?468-Another-option-for-0D-efan-control&p=5969&viewfull=1#post5969