Okay guys.
The victim is an 88 IROC with 305 TPI, auto and A/C.
My fans died today. I have read previous post and I started the troubleshooting procedures.
The fans will not come on with ADLD jumped, nor with the A/C on with coolant temp of 240.
The relay seems to be next to the battery with 4 wire going in. Red/black, black, gree/white and orange. I have 12volts on the orange everywhere. No clicking anywhere on the relay. Note: the car already has a Hypertech cool fan switch. Both fans dying at the same time leads me away from a motor failure.
Q1# Can I test the fans by running + and - on direct jumpers from the battery, fans should come on??
Q2# Can the ECM be the culprit with out any other driveability problems?
Q3# Any specific troubleshooting procedures are welcome.
The man or woman that helps me fix the car will become a hero and will be worshipped forever. Thanks

 

#1......yes, if you have the means, do so.
A direct link to the battery will(if each is still good) show you quickly if they work.
#2......Not a guru...but I doubt your ECM is at fault here...
#3......you already hit on what i would have suggested primarily in #1 w/the jumper idea.
You could also try testing the relay for it by jumpering it for physical verification it is good or bad. not to mention, if you have the means, test your wires also from the battery to the relay to the fan and ground.
Often a simple ground will fix many electrical problems....that.....fuses....and finding shorts.
Best of luck.....oh..I might not look like Vader...Just picture Boba Fett...COOLER
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[This message has been edited by Duffster (edited November 21, 2000).]

 

Okay
1. I have jumped the fans directly from the battery and they come on.
2. Replaced the fan relay located by the battery, no chnage.
3. Disconnected fan switch (pass sideof block) and grounded it to theframe no fans, relay was clicking.
Any ideas, I know I can rewire the fan setup but I would likethe factory configuration.
Thanks

 

The fact that both fans are inoperative helps to narrow down the problem. You say you've got 12 volts at the orange wire, so the culprit must be the tan wire. It must receive 12 volts (at the relays) with the ignition in the Run position. If not, it's probably a blown 20-amp FP Fan fuse. Have you checked this?

------------------
Willie

Supercharged 1987 305 IROC-Z, Daily-Driver, Emissions-Legal.
12.57 @ 111 mph.
12.04 @ 114 mph (50-hp nitrous).
http://members.optushome.com/au/downunder1/rides/willie/willie.html

1987 "20th Anniversary Commemorative Edition" Z28 Convertible -- Super Chevy Show Class Winner, 1998.

 

1. Tan wire shows 12V
2. 20 AMP fuze is good.
3. I' going to replace the harness that splits to the fans and has a large flat connection near the radiator. I previously had a short in it where I had to solder it. But it never caused trouble before, so I still think that isn't the problem.
Anybody else??
Thanks

 

So far, you've verfied at the relay connector:

1) 12 volts orange (regardless of key position),
2) 12 volts tan (in Run),

And you've jumpered directly to the fan to verify it's not the motor. Did you use the factory grounding circuit when doing this?

Next:
With ignition on, splice into the green/white wire at the fan relay. The fan should run.

Willie

 

Wille
As for splicing into the green/ white wire, what do you suggest. Ground the wire or ??

When doing a direct jump to test the fans I did + to + and - to - with the battery terminals, no frame grounding.

Talk to me Thanks

 

Cut the green/white wire at the base of the relay and ground the relay end. Turn the ignition on. The fan should run. I suspect it won't, but needs to be verified.

I have a feeling it's a bad fan ground. This would cause both fans to not function because both share a common ground. On my '87, the ground wire is bolted to the radiator support. I'd check this before cutting the green/white wire.

Willie

 

Okay here are my latest findings.
I un-plugged the harness from the primary fan (drivers side) and I conducted the following test.
1. Probing the positive side on the fan harness with the multimeter.
A. 0 volts with key in run and cold engine
B. 14 volts with key in run and ADLD in diagnostic ( A and B joined )
C. 0 volts with key in run and engine at 230+F
D. 14 volts with key in run and engine at 230+F with ADLD stimulated.
Seems that the signal from the ADLD is coming to the fan. The fan switch from the engine side dosen't seem to initiate voltage(Hypertech switch, I never had the car go over 200F with it).
The ground screw seems to be located above the battery on the frame. All the above test were also conducted with the engine running. I haven't tried to reconnect the orignal ground.

Just in case I think I'm ready for an alternate way of rigging the fans.

 

88,

You've verified that you have system voltage at the tan wire when the ignition is on. You also stated that when you grounded the control circuit the relay would energize. You said that you installed a new relay. And if you jump the fans directly to the battery, they operate.

All you have left is to find the high-resistance connection that is causing voltage drop when the fans are energized.

The relay is functioning correctly, so the ignition supply and ground connection through the sensor are both O.K.

The fans are protected by either a circuit breaker or fusible link, and it is most likely a fusible link on your '88. There are connectors at the fan motors, and the relay socket provides other connections. Any of these points can offer high resistance. You might be able to read voltage when the fans are disconnected, but that voltage may drop to zero when the fan load is applied to the circuit.

Troubleshooting Sequence

1. Plug everything back together and turn on the ignition.

2. From the back side of the relay connector, read the voltage on the orange wire ('E' terminal) and tan/white wire ('C' terminal) to chassis ground. You should get 12VDC on each.

3. Ground the dark green/white wire with a jumper to activate the relay (or at the switch). You should be able to hear and/or feel the relay click on.

4. Again check the voltage on the orange wire. You should have 12VDC to ground. If not, the connections to the fusible link are suspect.

5. If the voltage is present, check the black/red wire on terminal 'A'. There should also be 12VDC present there. If not, the relay is faulty or the relay socket is failing.

6. If the voltage is present, the only thing left in the circuit is the fan connector itself (connector C104 on the diagrams), and the ground connection to the fan motor.

Hope this helps. My guess is that since both fans failed at the same time, you'll find a problem at the fusible link or battery positive node connector located on the inner fender near the battery. Either that, or the ground point for the fans has high resistance to actual chassis ground.

------------------
Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

[This message has been edited by Vader (edited November 28, 2000).]

 

Thanks VADER
I will start your sequence of trouble shooting ASAP. Note near the fan relay there is a two wire black cylinder like a relay/ fuse. What dose a fusible fuse actually look like??? thanks Up Up and Away, with multimeter in hand.

 

Okay this evening I found out another thing.
The relay I was initally working with was 1 of 2 on my IROC there is one under the radiator cap (for the drivers fan) and one on the pass front side fender( I think for pass fan).
Well I didn't have time to do all the procedures that Vader offered, But here is what I did and learned.
1. grounded green/white on both relays and got a click on both.
2. had 12volts on tan and orange before and after grounding green/white
3. probed the black/red wire 0 volts--then grounded the grn/wht and got 12volts on red/blk on both relays.
4. removed the ground cable behind the pass headlights, clenaed area and added extra flux/solder to the crimp.
5. removed the connection from the drivers side fan,seated the 12volt light probe into the POS of the harness.
a. 0 volts
b. 12volts when the grn/wht is grounded on the radiator cap relay.

Okay I'll remove the entire sheath from all the cables. I'm going to check the motors one more time just to be sure. What dose the fusible link look like>/??
I what to thank everyone for the input.

 

I think Vader touched on what I believe the problem is, namely, from everything that you said, I would suspect that there is a bad connection from the relay pin to the relay socket which provides switched +12 directly to the fan motor positive.

You stated you have two relays. I don’t know how the relays are connected, but since you stated you have a Hypertech Fan Switch installed, I suspect that second relay is part of the Hypertech circuit, which switches the other relay to operate the two fans. You can easily confirm this by removing one relay from its socket and see if only one fan operates.

The way I like testing the fans (and associated wiring) is by doing the following. I know you’ve already done some of this, but for clarity, I’ll describe the procedure from the beginning.

1. Remove the relay from its socket.

2. To see if the fans operate, test it (them) by jumpering the two connectors on the RELAY SOCKET that have the thicker wires connected to them. One is the +12 feed (from the battery through a fusible link). The other supplies +12 to the fan motor. In your case, you would short the orange and black/red wires together by inserting a wire/paper clip/needle nose pliers/etc. between the corresponding sockets on the relay socket. This test can be done with the engine off since you should have +12 on one of the terminals (orange in your case) all the time since it is connected directly to the battery (probably via a fusible link). This will test everything between the fan/battery and relay socket.

3. On the same relay socket, confirm one of the other sockets with the thinner wires has +12 with the ignition on, and 0 volts (not ground) with the ignition off. This wire is connected to the battery through the ignition switch and fan fuse. In your case, it should be the tan/white (or black?) wire.

4. The other thin wire (dark green/white in your case) is grounded to operate the relay through one of the several switches connectd to it.

5. Reconnect the relay onto its socket. With the ignition on (to provide +12 to the relay coil), ground the relay coil at the appropriate wire (dark green/white in your case) to activate the relay. The relay should energize and the fan(s) should come on.

5A. If the relay does not energize, then either the relay is not getting +12 at its coil (due to a bad relay connection between the relay pin and socket connector, open fuse, open wire supplying the +12, etc.) or its not getting the ground (due to a poor connection from the relay pin and socket connector, open wire between the socket and the point where you are applying the ground, etc.) or the relay is inoperative. You can test the relay out of the socket by applying +12/gnd to the appropriate coil pins. There may be a diode connected across the coil in the relay, so make sure the proper polarity is applied to the correct pin if you test it this way.

5B. If the relay energizies (clicks) but the fan(s) do not come on, and you confirmed that the fans are okay (see #2 above), then I would suspect a bad connection between the relay pin and socket connector (where the black/red wire is connected in your case). It could also be the relay is not making a good contact when energizied, but since you have a new relay installed, I doubt this.

Based on what has been posted, I understand that:

ORANGE is +12 continuous from the battery (to one relay contact)
BLACK/RED is +12 switched to the positive fan motor (from one relay contact)
TAN/WHITE is +12 from the ignition switch, through the fan fuse. (to the relay coil) Your original post did not list a tan/white wire, but a black wire - you then later referred to this wire as being tan/white !??? Whatever color it is, by process of elimination, I would guess it'd have to be the positive for the relay coil
DARK GREEN/WHITE is switched ground (to the relay coil).

Since you confirmed that the relay operates (you can hear it click), you have the proper voltages on the wires, the fan(s) operate (tested only at the motor), and you replaced the relay (that would eliminate the relay switching contacts as a problem), that would make me look at the relay pin contact(s). Specifically, the contact that carries the +12 to the fan motor (black/red). While you did confirm that you had switched +12 there, there may be too much resistance to be able to supply the 8-20 amperes needed for the run and start conditions respectively for the fan motor, and yet enough continunity (lack of resistance) to be able to see a voltage without a load.

Since you tested the fans by applying voltage directly to the fan motor, you didn't test any of the wiring or connections between the motor, battery and relay connector. I would suggest you test all of those points by performing the simple test as detailed in #2 above. It should be a lot quicker than having to apply voltage directly to the motor. Especially important is confirming you have a good ground (which this test will do).

I had this problem on my ’91 Z28, but it was a poor connection on the socket/pin that grounds the relay coil, so the relay would never come on. To fix it, I removed the wire/socket from the relay socket base (use a micro screwdriver or a very fine pick by depressing a tab that locks the socket in place in the relay socket). I then compressed this socket so it’d make a tighter connection. I had to remove the wire/socket from the socket assembly to do this. Expand the tab so you can lock it back into place when reinserted.

I had the same problem with a connector on the rear hatch motor. Both problems were intermittant (a sure indication of a poor/weak/dirty connection somewhere), and both have never failed since.

//Stuart

[This message has been edited by Stuart Moss (edited November 29, 2000).]

 

Thanks for the help.
Here is one thing that happened about 2 years ago, the flat 5 or 6 pin connector that connects the engine side to the Y dual fan harness shorted out. The short actually was intermitten and it did burn out a hole on the harness, I think over the Black ground area. My fix was to drop solder into the orfice, it worked and the problem was fixed.
Okay I will do your procedures by Friday evening, Army is keeping me busy.

BUT I want to conduct this test.
1. As of last evening I know that if I disconnect the drivers fan and I insert a bulbed voltage probe into the positive terminal. I will get 12 volts at that terminal when the green/white wire is grounded at the relay under the radiator cap.
I also know that the fan will not come on if I reconnect the harness and the ground that relay again.
WHAT if I reconnect the fan harness and I ground the black wire that connects the fan 1 inch from the fan connection, then I will ground the grn/wht. This hopefully will turn on the fans.. WE will see
I want to thank everyone for their help.
I will win!!!

 

Just remember, as has been pointed out several times above, that just because you can measure a voltage with the load disconnected (the fan connector removed) does not necessarily mean that the circuit will be able to provide the necessary current under load.

There could be a marginal connection somewhere (the relay switch contacts, the relay pin/socket contacts, the fan motor connector contacts, the ground contact (screw to chassis?), etc.) that is making good enough contact to pass enough current to make a voltage measurement without a load, but is not good enough to pass full load current (the resistance of the connection may increase due to the increased current demand.

Just something to consider in your troubleshooting.

 

AND THE WINNERS IS??? ME!!
Okay the culprit was the 5 or 6 pin connector for the split Y harness that connects the fans. It seems that the black(Ground) wire was not continuing it's ground through the connector. Thus the fans weren't being grounded.
The current fix is a splice into the ground wire before the connector on the fan side, this new ground wire is mounted to the chassi
where the original resides. No more fears of getting stuck in traffic. Future fix is the purchase of a new harness.
I WANT TO THANK EVERYONE FOR THEIR HELP
This is a great board.
Next project is to fix the windshield washer sprayer. Are you ready???? Thanks again Rich