92blue

iTrader: (1)

As I'm sure many of you are aware, its kinda difficult to come across factory wiring thats in good shape. TPI cars are 14-21 years old now.

We are going to be building factory replicas of the dual fan wiring harnesses soon. I have been trying to find some originals to duplicate, but they are pretty difficult to find in decent shape.

I'm attaching a pic of the 87 version. Its the only year with the rectangular fan relay. The used one I picked up off an 87 to model had the loom missing, so I am not 100% certain on the exact exit location from the loom for the left fan connector in the pic. Judging from some pics online, it should exit further to the right.

I believe the 88-92 dual fan harnesses were identical, but I still have to look into that some more.

Anyways, if any of you guys would like to help out with some pics or measurements, it would be very much appreciated.

92blue

iTrader: (1)

pic...

3.8TransAM

I can pretty much swear the 89-92 harness are the same.

My TTA and both my 91's have the same fan harness setup for dual fans.

I can take some pics in car if I can find the digi, I really dont want to take them apart.

If your going thru the trouble of making the harnesses, I would higly suggest also making the rest of the wiring for them including relays as a weatherpacked/relayed kit.

I've rewired a few cars for duals fans and the biggest pia is any spicing of the harness for any reason almost always forces u to step up a fuse size or two from the standard 20 amp its supposed to have. This is following the GM wiring diagrams.

I havent managed to locate all the seperate pins to make a truly "new" harness.

later
Jeremy

92blue

iTrader: (1)

You mean adding the 6 terminal weatherpack connector to the engine harness (the fan harness plugs into that), and everything from there on back? Thats not a problem. I can set this up as pictured for those who already have dual fans and don't need to do anything else, as well as for those looking to add dual fans.

Was the second fan relay always part of the fan harness even up until 92?

The harness pictured is made completely from new parts, follows the GM wiring colors, and wire gauges are identical to factory. I will probably be throwing in some of the rosebud loom clips as well so the harness clips onto the fan assembly. At that point, it should be unidentifiable from a new GM fan harness (I am fairly sure these are no longer available).

If you can get some pics of how it is routed on the car, particularly the loom intersections points, I can see how they are angled. Thanks...

3.8TransAM

Ok

Either I will dig up the digi cam here or con a friend into it for me

later
Jeremy

thunderstick

i'm just asking the technical ?, but why would you have to step-up the fuses if you splice wires?

3.8TransAM

The "hit" when the fan intially turns on is the culprit 99% of the time.

Just a high amp draw for the initial turn on.

U start splicing and soldering(and I used equal or larger wire for the splicecd in rebuilt sections) u raise the resistance a little bit.

Tends to be enough to push the 20amp factory to the edge.

The tend to work a few times and than burn the fuse out. Doing the same with a completely made harness or original factory and its been ok.

later
Jeremy

thunderstick

thanks - just more "nice to know" info...

jmiller

I got tired of the second fan not coming on at all, and the first one coming on at what I consider too hot already.
I installed an adjustable thermo kit in the radiator and wired both fans together. Set the adjustment to turn on at about 170. Never have blown a fuse or had any other problem. Been working perfect for about 5 years now.

Mkos1980

iTrader: (8)

I've seen my GF's has the weather pack connector, but mine is just integrated into the whole harness. How would you reproduce that?

92blue

iTrader: (1)

Well, I've been brainstorming somewhat on what the best layout would be for a dual fan conversion wiring kit. Developing something to integrate with a single fan harness will have some compromises, and I'm not sure what would be the best way to proceed.

I took apart an 88 TPI harness a few days ago to take some notes and measurements on the fan wiring, as well as on a TBI harness.

My original intention was to create a duplicate of the dual fan circuit throughout the entire harness. The problem with going with this route is that it will involve quite a bit of work to integrate with a single fan wiring harness. Undoing loom and tape at intersections, then redoing everything with the harness in the car is a royal pain. Not to mention that it seems like an overly complicated way of setting up a rather simple circuit. This could be offered as a service as well as a product, but again, this seems like a complicated way of going about this.

How important would you guys consider

1) Ease of installation
2) Factory dual fan layout (relay locations, fan harness being separable from main harness)
3) Pricing
4) Flexibility on fan control (same product having multiple methods to turn fans on/off depending on preference)

I personally like having the ECM control one fan, and the fan switch control the second. However, many of you guys have different preferences on how to set them up. Both controlled by the ECM? Manual controls?

3.8TransAM

Well, heres my two cents from a lot of testing, multiple engine combinations, and tons of datalogging and chip burning and I'm sure lots more stuff to learn.

1) The second fan controlled by the fan switch is great, rather have at least one fan running than to lose both of them. Get a GN fan switch and it will come on at 195.

2) Primary fan by ecm control is my preferred method(just like factory) but the fan settings tweaked obvioulsy to work in the parameters of a 180 deg t-stat.

3) Running both fans all the time is not necessary, unless you have other issues(or jamming a big block in it with a stock radiator lol)

4) T-stat temps below 180 on the street arent a good thing. Specially with people who do no tuning of their own. This combined with stupid(read extremely low fan turn on temps) on the street basicaly doesnt allow your oil to get hot enough to burn off contaminants(read paraffin build up, water/condesnation/etc)

5) Manual jumper wouldnt be a bad thing to stick in there, would work nice when autocrossing or dragstrip for cooling the car down in the pits.

6) I would prefer to see it come in a factory style. Most people I know would tend to do it this way. The jumper in place to turn both fans on would be anice upgrade, or just include it as is in the harness and leave the hookup to the installer/owner. Your gonna need the relays and fan wiring either way :-)

7)Could also make a harness minus the weatherpaks for temp sensor and use a rheostat type fan control(push into the rad fins)

My 4$ worth lol

later
Jeremy

RPOL98

one other note worth mentioning is that once you get over perhaps 30 mph, the air flow through the radiator probably makes the fans redundant, just sucking up amps, especially if the fans are triggered by, say, an electrical 180* temp switch. On my "other" car, with my own concoction of dual fans, both fans are on even while I'm on the freeway doing 60. Of course, that's on my list of things to do, to fix. haven't gotten around to it yet. but you can really see the voltmeter take a big dip when those two fans switch on, not to mention that it sounds like an airplane taking off when they switch on.

92blue

iTrader: (1)

Thanks for your input guys, I appreciate it. I have a tendency to overcomplicate and overanalyze even simple things lol.

RPOL98, this is one of the areas of compromise I've been debating on my own. Your factory ECM can shut off the fan at any vehicle speed you want. Although the factory circuit only gives the ECM control of one fan, it can be setup so that the ECM has full control of both, and you can set different road speeds at which they are turned off. However, this involves reprogramming proms, and this kind of talk will confuse/scare off folks that are looking for a simple solution. But lets forget that for a second. Suppose that wasn't a problem. Running a lead through the wiring harness bulkhead connector to give the ECM control of the second fan would be a royal pain. I would try to avoid making a product that will require you to drill through the firewall to run the extra lead to the ECM as well.

3.8TransAM, I appreciate you taking the time to state your thoughts. I agree pretty much with everything you've mentioned. this will probably end up having some flexibility to allow the installer to hookup and control as desired. I didn't know the stock GN switch grounded at 195.... thats interesting. I thought it was in the 210-215 range.

I've yet to tinker with a dual fan install. Although I live in the hot, humid climate that is Miami, Fl, I haven't had a need to go to dual fans. My single TBI fan is enough to keep engine temps below 215 even in stop and go traffic. I left the fan wiring as it was on the TBI harness when I converted to TPI. I'm running a fan switch which comes on at 200, off at 185, and a stock replacement alum. radiator.

I believe I've made up my mind on how to proceed at the moment. I think I'll be putting together a "kit" to integrate with the single fan wiring such as the one found on an L03 setup. The fan wiring will be separable from the engine harness just like on the Tuned Port harnesses. It will be set up for ECM as well as manual control.

I'm going to be installing this on my daily driver, and will try it out first before offering it. I may decide to make some changes at that point.

I'll post again whenever I have some news regarding the kit. IT may be a while before I have a final product. I have the necessary connectors and terminals on order already, but I don't exactly have an abundance of time.

85_SS

iTrader: (5)

Any update on such harnesses? I would be interested in a pigtail male plug for the main fan wiring.

92blue

iTrader: (1)

So far, I don't have such a kit ready. We have been quite busy lately, and I seem to have a chronic problem where I start and work on 50 projects at once...lol. Takes me forever to get things done that way.

What I do have is the removable section that runs from the engine wiring harness to the fans. Those are listed on our site as of recently. I don't have the male end thats part of the engine harness however, only the female end.

85_SS

iTrader: (5)

Thanks for posting back. Are you also tpi_parts on ebay? If so I send you an email there as well that you can disregard

92blue

iTrader: (1)

Actually, yes I am. Haven't had a chance to reply to some recent emails yet. What was your ebay id? I don't want to mix you up with someone else.

85_SS

iTrader: (5)

Same as my ID here. I had inquired about a custom harness on the engine side - sounds like you have your hands full with other project though

Do you know off hand the PN's of the male plug for the relay and the main harness? ...and do they come with the contacts inside them for the wire to crimp on to? I may attempt to make my own harness.

1993formulav8

Not true, I have an 88 car that I am looking for the fan harness for, my buddy has a 92 car. My car has a 6 male weather pack connector, his has a 5 male weather pack connector.

92blue

iTrader: (1)

Do you think you can post a pic of the 5 way connector you mentioned? I have picked up a variety of fan harnesses up to 92, and every one has been the same 88 through 92. However, I realize that alot of times people assume the year when they put it up for sale, and alot of times they aren't correct.

85_SS, I don't know the part number for these. Send me a PM though, I might be able to help you locate what you need.

85_SS

iTrader: (5)

PM sent

I H8 WWD

iTrader: (5)

Any updates? Also what is your site called 92 blue?

Grim Reaper

You guys are aware that it is possible to operater BOTH fans with the stock ECM on SD cars? You just jump (or move) Black D12 to Green F8. Then the second Fan is completely controlled by the ECM.

In fact, I changed my settings for the Secondary Fan comes on first and the Primary Fan second. The Secondary Fan is so seldom used, it avoids wearing out the Primary Fan. But, if my engine is hot (and the fan is already on), should I turn on the A/C, I will have two fans working as the A/C turns on the Primary fan.

The above setup is the BEST I have found...and you don't need any silly Fan Switches or anything. Just either "jump" or switch Black D12 to Green F8.

And MAF cars use a different wiring harness from SD cars. SD cars (1990-92) have three ECM connectors while MAF cars have only two ECM connectors. You can make a MAF harness work on an SD car (if you swap all the pins and use three connectors)...but it still cannot support a "true dual fan" setup like I mention above without running separate wire.

92blue

iTrader: (1)

Actually, I have been working on a flexible dual fan wiring setup for a while now, along with a bunch of other projects at the same time (thats why it takes me forever to get things done lol). I finally came up with a system that I am happy with in the sense that it allows the installer to configure very easily in a variety of ways, and the configuration can be changed even after installation.

You can control each fan by any combination of the following: ECM, fan switch, toggle switch, and A/C request.

Our website is www.tpiparts.net, we are one of the board sponsors.

We have had reproduction fan harnesses (the portion that is removable) available for a while now. They come in two versions, one for 87, and one for 88-89. The difference being the relay connector.

GRIM REAPER, I am aware that the 730 ECM has the ability to control two cooling fans. However, not everyone would like to do that, as it requires programming if you do not like the factory fan turn on temps. Also, no CTS reading means no ECM controlled fan operation. How many folks on this board are driving around with a bad CTS, or a bad CTS connector?

The problem is, the best solution is different depending on the person's needs and likes. Personally, I like having a redundant system. In other words, having the fan wired to come on whenever any of the following request it: ECM, fan switch, A/C, and perhaps even a toggle switch. If one system fails, the other will keep the fan running. The only problem with this is, if one system fails, you may not know it.

I'll post some pics of what we have built soon. Should be sometime this weekend.

Grim Reaper

A bad CTS will trigger an SES code. And, whenever you have an SES code, it automatically turn on the fans. That's part of the "Safe Mode & Limp Mode" features of the programming.

Because of the "Fail Safe", you have automatic redundency - except if the ECM fries...then you are going no where.

I prefer to keep things simple and effective, with a minimal alternation to the wiring. I run a "tight" cooling temp with my 180* T-stat and seldom run hotter than 185*.

Maybe if you learn more about the ECM & programming, you may just find you are doing a lot of hard work for no reason. The ECM always remembers the temperatures you set the fans to come on & off, without requiring any intervention from a human.

92blue

iTrader: (1)

You won't always get an SES light when you don't have a CTS signal. It hasn't happened to me on a TPI vehicle, but I have personally driven a TBI setup with the CTS unplugged running a 7747 ECM for about half an hour straight without getting an SES light. SES light was functional, paperclip test showed only a code 12, and the CTS issue was found by datalogging. Laptop showed the CTS reading at -40 something. I don't have a service manual for that setup here, but looking at a TPI service manual, Code 15 is supposed to come on after 3 seconds with a reported CTS temp of less than -49. I don't have the source code for the $42 mask, but I seriously doubt GM coded it much differently.


Yes, in limp home mode the fan will come on automatically. Not all SES codes will cause the ECM to run in limp home mode. A good percentage of them actually will not cause limp home mode.

Regardless, what we are talking about makes little to no sense for someone to add to a factory speed density TPI harness. Thats not the intention of our harness. For someone looking to add dual fans to their car however, there are benefits. Not every ECM can control two fans. And not everyone with a TPI/TBI setup has a thirdgen, and retrofit harnesses leave the fan wiring up the the installer.

Ask five different people how they want to have their fans controlled, and you will get five different answers.

Grim Reaper

TBI is different than TPI; and, SD (7730 w/ 8D) is different than MAF (165 w/ 32, 32B or 6E).

When the CTS stops functioning, it will trigger an SES code 14 (too High) or code 15 (too low) on 7730 w/8D. In both cases, the primary fan will come on.

Anyway, I thought you were looking for info from people with the factory dual fan (TPI cars); and may be interested in how to make an improvement on the stock SD system with no changes to the wiring other than moving one wire in the connector and a simple change in the Fan Temp settings in the eprom.

Drew

iTrader: (58)

Both my 91 Formula L98 and my spare 91 T/A / Formula L98 harness have all the fan wiring integrated into the main engine harness, it's not seperate like the harnesses that usually show up.

92blue

iTrader: (1)

I'm aware that there are significant differences between a $42 mask, an $8D mask, and a $32 mask. I would be very surprised if the requirements for setting a code 15 are different at all between a TBI and TPI application, or among MAF and SD TPI systems. When I have some time, I'll take a look at the $42 and $8D hacks and take a look for myself.

The original intent of the post was to gather information on building reproduction fan harnesses (the removable portion found on Camaros). Another board member brought up the topic of building a harness to convert a single fan setup to dual fans. The discussion at that point was not to improve on the stock dual fans setup, but rather on how to control the fans on a harness intended to convert from single to dual fans.

I appreciate you trying to help, but I don't think you fully understood what I was referring to with respect to what a new harness would intend to accomplish.

To my knowledge, all Firebird TPI harnesses with dual fans have the fan wiring integrated into the engine harness. The 87-89 Camaros with dual fans have a removable fan harnes. Starting at 1990, it seems they were part of the engine harness as well.