Can somebody Help a brother out
 

Hopefully someone can help me out. I'm in the process of figuring out why my electric fans arent working on my 94 TA. I narrowed down and I need to find out if the computer is telling the relays to turn fans on. Is there anybody near Rockaway Mall that can either lend me their OBD1-usb cable or let me plug my car into their setup. I will barter beer, food, soda, money,tools,car parts. whatever is reasonable. Also, if any electronic wizards on this site want to try to figure out with me, I'd appreciate it.
Thanks a million

Are you positive the fan itself work?

To eliminate the relay and fan I would personally jump the two of them. If you look at the relay it should have a wiring diagram on it but i think you are jumping terminal 87 and 30 IIRC.

I don't know if that car uses one or two temp sensors but you can have a faulty sensor

Check ground connections to for the fan also.

I would check the entire system before looking into the PCM unless you have already done so.

What have you checked?

The fans work when I ground plug #2 on #3 relay. The fans also work when I plug in my OBD1 code reader under dash. I swapped relays and still dont work. I also replaced ECT sesnor with nothing. I checked all of the relay grounds/power and all seemed good. The only thing that wsa weird was on SHObox website they had the relay plugs labeled differently than is on my U/H fuse panel.

I also unplugged the PCM BAT fuse overnight but nothing. I just ordered an SLP manual fan switch that will mostly solve but I'd rather have the root of the problem fixed. Thanks

You have a wiring diagram you are basing everything off of?

No blown fuses, it sounds like something is shorted somewhere. I would check the relays ground first.

You said you don't know if the PCM is commanding it to turn on right ? Which ECT did you replace the one in the water pump ?

Yes, I based everything off of the one on SHobox website. No blown fuses, Relays are fine. Fans work fine when I ground the pin that would be from the ECU. That makes me think that its the ECU but when I plug in the code reader it jumps the pins and turns on the fans like its supposed to. According to Shobox, if the code reader turns the fns on, the ECu is doing its job. I replaced the ECT in the water pump. I didint bother doing th eCT in the head cause the gauge is reading right.

Temp sensor in waterpump is for the computer. Let the car get up to temp that commands fans and see if terminal 85 on the relay is grounded. This would be the pcm commanding a ground to switch the relay. Terminal 86 and 30 should have constant power, gm has them jumped like that underneath. Does the car have a working a/c system? If so, turn the a/c on and see if both fans come on after a little bit of idling.

Report back.

Sweetbmxrider,
Thanks for the reply, Terminal on which relay. I have the three relay. I'm assuming the #3 relay?? My AC doesnt work so it wont turn on the fans.
By the way I have a couple old BMX's I'll post them up sometime.

Relay #1, it controls the driver side fan.

Nice, I'll try that in a little bit.

No problem, I thinks its 210* kicks on low speed fan.

Ya, i think your right.

It is.

Does anybody know what temerature that the computer starts to retard the timing. Whats kind of weird abut my car is it gets up to maybe 230 quickly and then really slowly starts to go down to 210. When it gets hotter, it starts to run a little rough, i think the computer retards it.

IIRC secondary fans come on around that temps and retard the timing. I think it was 230.

Im pretty sure with the three relay system that I have, the fans are run together where at 210 both fans come on low speed and at 226 or 230 both fans kick on high. I know that my high speed fans arent coming on and maybe thats why I'm getting up to 230. Maybe just the low speed fan is able to get the temp back down to 210 after they kick on?

Sweetbmxrider, I checked #85 on relay #1. With car running hot it is not getting ground from computer. It does get ground and turns on the fans when I plug in my code scanner.

So you were only able to get the fans to operate with the code reader plugged in? Otherwise the relay wasn't grounded and the fans won't come on? Terminals 86 and 30 are hot?

Yes, exactly..Is there a way to see if the ECT sensor is telling the ecm to turn fans on without scanner?

Like a voltage tester inline to test the voltage as the temp rises or something

Resistance
177 ohms at 212 deg F
241 ohms at 194 deg F
332 ohms at 176 deg F
467 ohms at 158 deg F
667 ohms at 140 deg F
973 ohms at 122 deg F
1459 ohms at 104 deg F
2238 ohms at 86 deg F
3520 ohms at 68 deg F
5670 ohms at 50 deg F
9420 ohms at 32 deg F
16180 ohms at 14 deg F
28680 ohms at -4 deg F
52700 ohms at -22 deg F
100700 ohms at -40 deg F

After sitting overnight, the engine coolant temp sensor should be within 4 degrees of the intake air temp sensor.

You would need to get to check across the sensor. One side on the ect the other at the pcm where the ect goes to the pcm. That will check breaks in the connection and what the ect is reading.

Check that and check voltage output of the pcm to the fan right at the pcm before the fans should kick on and after thy they should be on. This way it can almost eliminate that as a possibility

Send a link with the wiring diagram if you could

Thanks guys. next step was checking exactly what last 2 posts said. Its kinda hard to work on car with newborn twins........The wiring diageam is under electrical section of shobox website.thx again

Yeah I can imagine that is no fun.

When I tried " googling" that site just got shoes. Il try again harder tomorrow