TBI Electric Fan Swap

Ok, so I've read this thread: [You must be registered and logged in to see this link.] and it seems the instructions are more for the LT1 cars. Is there any difference when swapping this into a LO5 TBI? Any other parts needed besides whats mentioned in the other thread? ALso, will I be able to use the Innovative Wiring harness?

I am soon to undergo a similar change to Shammoo. I got most of the parts from Mike (200OZ) Radiator, both fans attached , upper shroud coolant lines overflow tan fuse box and wiring harnesses.ts

A thread with pics, I beg of you sir.

At this point, I don't have much to show other than pictures of parts laying around in my garage.

lakeffect wrote:

At this point, I don't have much to show other than pictures of parts laying around in my garage.

No, I know you dont. But when you do install it, that step by step would be super duper.

Better yet. you can come for the weekend and get your knuckles dirty with me.

Here's a few other internet sources. Sometimes I find I get a better understanding or description from some authors than others. It all helps the cause in the long run. It all advances my knowledge.


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lakeffect wrote:

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I posted in that one, and it loops back to the electric fan swap here. Problem being is that it was an LT1 thread so again, dunno how different, if at all, it;ll be for my car.

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You're welcome.

The issue with installing electric fans in the TBI cars is how to signal them. The LT1 cars are signalled from the ECM but the TBI cars need a sender unit. Unfortunately, both available ports are occupied by the gauge sender and the computer sender. Didn't need the puter on the diesel, so used the sender port on the water crossover.

Drilled and tapped a port on the thermostat housing for one in the Caddy (until I got Tunercat and changed the turn on temps) and back fed into the relays. Worked well except it kept throwing a code.

If doing it again on a TBI, would use an aftermarket sender (35 bucks at local auto parts store) that mounts through the rad but would use two relays, one for each fan, as with both running you can exceed the 40 amp spec on the supplied single relay. You will also need another relay (your up to three now) to turn on the passenger fan when the AC clutch kicks in. You need the third relay as the AC one is wired opposite to the temp relays (temps are turned on through the ground while the AC is turned on with power side of the relay)

Will try to make up a schematic if anyone is interested.

Bill

I'm running a different ECM that all the "normal" TBI guys, as I'm running TPI now. It's  known as a 7730 ECM or 730ECM. It has provision for sending a signal to a relay via one of the pin outs. It works of the the coolant temp sensor (CTS) that is already there.

I have not looked at the ECM pin outs for a TBI in a long time. I would not be surprised to see at least one pin out available. It could turn on both fans rather than just one, but need to see the pin outs first in my FSM for 1993's.

one of the quoted articles  listed above says this about pin outs already

"3. Wire the PCM:
Connect PCM pin, Part # 12084913, $1.11 to a roll of 20 gauge wire. Remove the Red 32 pin connector from the PCM. Open the plastic cover over the wires. There are 3 little plastic tabs that allow you to do that. Insert, "Push" the pin into position # 11. They are numbered on the connector. That is the ground signal from the PCM to turn on the relay. You can see that the pin goes all the way in as it is made of clear plastic. Reinstall the connector on the PCM. Route the wire to the location of the relay."

7730 ecm is for a camaro,. it has fan on command,.

Nick

Absoluely. Also for Corvettes and Firebirds. It has two dedicated pin outs, and I plan on using both.

The 93 FSM should help answer the bottom line.

Didn't check the ECM pinouts as I wasn't using the thing with the conversion. You are probably right, yet all the TBI "B" cars I have seen had mechanical fans so assumed there was no provision for fans. Even if there is, is there any provision to change the "fan on" temps?

Would still suggest multiple relays as using only one burns it out quickly. That plus the AC one.

Bill

The fan setup on the 93 FWs would bolt up to the LO3/5 cars directly, and you may even be able to grab some of the other parts for the swap. The 93s had LO5s in them. It would be a lot easier than hunting for parts.

I was thinking about that. Just need to find a '93 Fleetwood in the yard.

Sort of a needle-in-a-haystack kind of thing.

I've seen a couple in the yards in the last 2 years. I missed the parts from one that was nice, and the other was heald together by chewing gum and bailing wire. I have the lower mount and the fans. I need the upper mount and periferals. I really should get the FSM, so that I can find out what parts I need.

I had a set of those Caddy fans a few years ago, tossed 'em last year because they didn't fit my Buick right.

Mike

200OZ wrote:

I had a set of those Caddy fans a few years ago, tossed 'em last year because they didn't fit my Buick right.

Mike

BOOOOOOOO

Hey Bill I would really appreciate that schematic when you get a chance!





Oh and does anybody know what a schematic is?
Thanks
Jim Gordon

200OZ wrote:

I had a set of those Caddy fans a few years ago, tossed 'em last year because they didn't fit my Buick right.

Mike

They are different from the LT1 fans.

I checked the 1993 Caprice FSM for pin outs concerning fan control.

There are none listed specifically for it.

What might be worthwhile is seeing if the 1993 Buick or Olds used the same computer part number. If so, and an electric fan was apart of the towing package (or similar use) there might be a pin designated for it already.

While working with other ECM's from GM, I've found just because it's not listed doesn't mean it isn't there.

lakeffect wrote:

I checked the 1993 Caprice FSM for pin outs concerning fan control.

There are none listed specifically for it.

What might be worthwhile is seeing if the 1993 Buick or Olds used the same computer part number. If so, and an electric fan was apart of the towing package (or similar use) there might be a pin designated for it already.

While working with other ECM's from GM, I've found just because it's not listed doesn't mean it isn't there.

None of the B-body cars from 91-93 used electric fans. The only compatable 93 to use electric fans is the FW.

Fred Kiehl wrote:

lakeffect wrote:

I checked the 1993 Caprice FSM for pin outs concerning fan control.

There are none listed specifically for it.

What might be worthwhile is seeing if the 1993 Buick or Olds used the same computer part number. If so, and an electric fan was apart of the towing package (or similar use) there might be a pin designated for it already.

While working with other ECM's from GM, I've found just because it's not listed doesn't mean it isn't there.

None of the B-body cars from 91-93 used electric fans. The only compatable 93 to use electric fans is the FW.

With that in mind, here is the pinout of a 93 fleetwood ECM from alldata. A2 and A3 look to be what your after. But it gets complicated, if you look at the 93 Roady, A2 is not connected while A3 is connected to the canister purge. Both images are of the 93 fleetwood connectors.
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And in retrospect, here's the 93 Roady connectors
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It looks like you would have to have the FW computer and harness to get the wiring anywhere near correct.

Flasheroo wrote:

Hey Bill I would really appreciate that schematic when you get a chance!

Oh and does anybody know what a schematic is?
Thanks
Jim Gordon

Jim:

Sorry for the quality but seemed to have lost the program I used to use to create these things. Your going to have to settle for a paint program.

The standard Bosch 40 Amp relays are more than sufficient (same as the fuel pump and AC relays already in our cars). If you don't care if your fans continue for a minute after you turn the key off, you can use a feed off the main power terminal (live all the time) to power the fans. Can't remember if the TBIs have any high amp fuses in the system that you can use but the main accessory fuse should be big enough.

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Bill

Thinking I'll stick to my mechanical fan, then....

Fred Kiehl wrote:

It looks like you would have to have the FW computer and harness to get the wiring anywhere near correct.

At first thought, one would think so Fred, but as mentioned, there are uses for some pin outs that GM doesn't tell you about or want the average person to know. I use a pin on my 7730 ECM that gets an input from a wideband AFR sensor and gauge. It wasn't original equipment on any 1992 car that my ECM is from. They didn't exist on any GM engine at the time. But the pin was there.

I've heard theories that it was how GM collected data during prototype development for the original chips during testing. What little wideband stuff was available was incredibly expensive back then. After burning a chip, they didn't need expensive wideband stuff on it anymore. Much cheaper narrow band would work just fine.

For our purposes, the easiest way I can think of to verify it's use, would be to hook up pin A2 to an LED and the other end to a 12 volt source. It is grounded through the ECM. when the circuit tunrs on.

Idle or run the engine to get it hot. Watch your temp gauge for relative movement. At an appropriate point as the temp climbs, if the LED comes on, you've just found out something GM didn't want you to know.


That Pin A2 can drive a relay for an electric fan, and is already set up for it to happen.

Check to make sure that as the temp comes down , that the light also goes off.


Dave "PINHEAD" Buchholz

convert2diesel wrote:

Flasheroo wrote:

Hey Bill I would really appreciate that schematic when you get a chance!

Oh and does anybody know what a schematic is?
Thanks
Jim Gordon

Jim:

Sorry for the quality but seemed to have lost the program I used to use to create these things. Your going to have to settle for a paint program.

The standard Bosch 40 Amp relays are more than sufficient (same as the fuel pump and AC relays already in our cars). If you don't care if your fans continue for a minute after you turn the key off, you can use a feed off the main power terminal (live all the time) to power the fans. Can't remember if the TBIs have any high amp fuses in the system that you can use but the main accessory fuse should be big enough.

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Bill

This appears to turn both fans on when the engine gets hot, and one fan when the A/C is on and engine is not hot, but never one fan when it is below a threshold with the A/C off. Originally the fans came on at different temperatures with the A/C off. Would that require a second sensor with a different temperature range, or is there another way to make the fans independent of each other.

Fred Kiehl wrote:

This appears to turn both fans on when the engine gets hot, and one fan when the A/C is on and engine is not hot, but never one fan when it is below a threshold with the A/C off. Originally the fans came on at different temperatures with the A/C off. Would that require a second sensor with a different temperature range, or is there another way to make the fans independent of each other.

Fred:

Your right in that you would need two sensors, or if you could find one with two settings ??? to get the staged turn-on. I think I've seen a dual adjustable sender (thru the rad type) from Kool-Rite that would also work. Would still need the main relays as these systems are not very dependable when you draw big current thru them. Don't see a problem with turning on both other than power use but if you could find another sender location this would also work.

Turns out I shouldn't be doing this kind of thing late at night. There is no need for the main power feed to be switched. You can hook up the main power directly to the power buss on the passenger fender and connect the signal power from both relays to an ignition switched circuit (they only draw about 300 MA). This would be easier.

New drawing:

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Sorry for the temporary brain flatulation.

Bill

Thanks guys for making this a project that I am more than willing to attempt this weekend!
Take Care All
Jim Gordon

so why not use a 7730 ecm?

You got one?
Jim Gordon

phantom 309 wrote:

so why not use a 7730 ecm?

My old ECM had two connectors. The 7730 has three.

I still think one of you guys should connect pin out A2 with a LED and 12v on the other side. See if it lights up around 200*F

Just want to throw out another possibility for anyone overwhelmed with the DIY route: [You must be registered and logged in to see this link.]

With 3 pins ,does that mean 1 pin per fan and the third pin activates both fans?
Jim Gordon

Olds Weighty Eight wrote:

Just want to throw out another possibility for anyone overwhelmed with the DIY route: [You must be registered and logged in to see this link.]

Used these on the Locomotive. Lasted about 90 days. Would probably have a longer life if you used them as the signal voltage for the additional fan relays only. Wired as primary power they just coudn't cut it. The Keep- Cool ones lasted a bit longer but not much.

Bits for the above should cost about 1/2 of one of these kits and should last alot longer.

Bill

Yes I looked at those when I first got my fans.Another question I have is will my 105amp
alternator be able to keep up with both fans on and the AC running all together?I was going
to upgrade to a 140 amp alternator but do I have to do anything else to the electrical system
when I install the higher output alternator?
Jim Gordon

The 140 Amp Alternator is a good idea regardless. This is a straight swap as both use the two wire field/alt light plug. That may not be the same but just a splice job to use the correct one.

Even if both fans are the 150 watt versions, if the alternator is working, than they only draw about 11 Amps each when running. On start up they draw twice that (22 Amps) but only till they get spinning. Your AC really doesn't pull that much. Its just the blower motor and the compressor clutch. Maybe 10 amps total. Headlights are a biggy, especially high beams and that 4,000 watt amplifier in the trunk, when set at maximum thump, can draw upwards of 300 amps (like your starter running all the time). Theres a reason the manufacturers are specing starter cable to power these things.

Bill

No 4000 watt amps for me as my 56 year old ears are already hurtin from all the shooting I
did even with the earmuffs.Jim Gordon

Flasheroo wrote:

You got one?
Jim Gordon

TBI stuff??
nah,. that was waay back when,. BTDT.
I'm not the one making things overly complicated here, so i don't need a 7730 pcm.
But i sure a **** would be looking around to acquire one IF I needed it,.

Flasheroo wrote:

With 3 pins ,does that mean 1 pin per fan and the third pin activates both fans?
Jim Gordon

Not three pins, three big plastic connector plugs. Within each plug are a number of pins. What I'm saying is physically the TBI and my TPI ECM's are not the same configuration and not interchangeable.

I'm bringing back this thread from the dead.
I'm starting to get my Electrical dual fans in order. I was wondering if anyone has taken the time to hook up a test light to pin A2 of your TBI ECM's yet

I'm still curious if GM left the connnection there for you to use. remember the LED is grounded through the ECM not powered by it. So that means you need a 12 volt source on the other side of the light to make it work. Don't ground it, as you'd be grounding both sides of the circuit.

I have TPI and a different ECM (7730)with pin outs for the purpose. I'm hooking up my own test lights this morning to see if My idea worked or not.

Guys it may seem alittle far fetched by why not just use garys wiring kit

1phastsswagon wrote:

Guys it may seem alittle far fetched by why not just use garys wiring kit

I believe Gary's wiring kit is for an LT1 car.

He offers a wiring kit for those who are doing an elec fan swap.

This wiring harness kit comes with everything to wire up your fans when installing an electric primary fan on your car that came factory with a mechanical fan.

Kit comes with 40amp maxi fuse, fan relay, loom clips, all the wire with factory terminals crimped and soldered on, PCM to fuse box (20 gauge wire), 40amp fuse to relay (10 gauge SXL wire), fuse to relay (18 gauge wire), primary and secondary relay to 4 pin fan connector with ground wires (10 gauge SXL wire), 4 pin connector to both primary and secondary fans with loom so it has the factory look.

$85.00

May be a stupid question. What would it hurt to have the fans just come on when ignition is turned on and runcontinusally? Besides wear and tear on elc. fans?

chevy5seven wrote:

May be a stupid question. What would it hurt to have the fans just come on when ignition is turned on and runcontinusally? Besides wear and tear on elc. fans?

motor would run a little cooler,.take longer to warm up,.
but other than the aggravation factor of them on all the time,. it,d work,.
check engine light on can make lt1 fans run continuously.

Nick

The whole idea is to have the fans work only when needed to lower the power consumption. If they are going to run all the time, you might as well just use the mechanical fan with the viscous drive.

Fred Kiehl wrote:

If they are going to run all the time, you might as well just use the mechanical fan with the viscous drive.

Ohhhh so true. That and burn them out quicker if running all the time.