Project86B4Z

i recently did a dash swap along with changing the temp switch to a sending unit the works properly now but now there's no fan operation. there was a point where it only came on with the ac couple of hours ago now it does niether. i also changed the cts as last resort and the relay and motor is new.

Maverick H1L

iTrader: (8)

If I'm interpreting your post right, you replaced the idiot light switch in the driver's side cylinder head, behind the A/C compressor, for a sending unit for a gauge cluster...

I'm also going to assume your alternator is working, since it's on the same circuit as the coolant fan relay...

Put a wire in the ALDL by the radio and HVAC switches to pull codes (top right corner terminal and the one just to the left of it) and turn the ignition on. Fan should run. Take wire out of ALDL.

Pull the connector off of the switch in the A/C line running down the pass side frame rail next to the coolant bottle with the ignition on. The fan should run. Put connector back.

Pull single wire connector off of fan temp switch in the rear of the pass side cylinder head (same position as driver's side gauge sender but on other side of the engine) by the lifting eye by squeezing it and then pulling it off of the switch. Stick something in the terminal (such as a nail, screw, or other metal object) in the center with the ignition on and point connector at a bolt or engine part (other than the alternator). Fan should run.

If the above fail... Disconnect the relay. Jump the red wire to the black one with the red stripe. The fan should run. That proves the fan is able to work. Also check for power with a test light or meter on the tan and red wires. There isn't any power on the tan wire with the ignition off...

Swap the relay with one of the ones next to it and try the fan temp switch test (the third one listed) again as it's easiest. The fan should run, and this finds a bad relay.

Project86B4Z

I discovered the green wire in the relay was disconnected.
.connecting it didn't do any good..
. I ran voltage check with ign on and ALDL grounded and got 12
54 volts on all wires but what ever reason the power is not hitting the fan

camaronewbie

1) if you have a single fan, and a CTS - you don't have a fan switch in the pass side head - so ignore that - the ECM controls the fan, and gets it's readings from the CTS.

2) reconnected the green relay wire to what? It's supposed to run directly to the ECM.

Project86B4Z

The green wire on the relay

Maverick H1L

iTrader: (8)

1. You mean to tell me that the green fan switch wire that I pulled out of my factory 87 harness, with a CTS, didn't exist (along with the fan switch I replaced on my 2.8 before it was swapped out)? It was a backup on the older system, which his 85 has...
2. The green relay wire splits between the ECM and the backup fan switch... Which is why I said to jump the fan switch to ground with the ignition on to check the relay...
Might want to look at this: http://92b4crs.tripod.com/86wiring/dia-pics/31-0.jpg

OP, did you jump the red wire or the tan wire to the black/red wire at the relay? If the fan didn't run then, there is a break in the black wire between the relay and the fan motor (black/red wire is the power wire leading to the fan motor).

Project86B4Z

i jumped the green wire on the relay to the black wire on the relay and the fan comes on and stays on even with the ignition off. After that i have to tap the relay to turn it off and its a new relay :P

camaronewbie

Sorry - Maverick is right maybe.

I'm totally confused on exactly what the OP has for wiring, since his sig states a 2.8l V6 (which didn't come in a 1985 car), yet he also states 1992 Z28.

It might help if we knew exactly what it is that you have ....

See Maverick - I was looking at the wiring diags for a 2.8l V6 FI motor - and THAT setup has no fan switch at all : http://www.austinthirdgen.org/mkport...ine_wiring.gif.

If "tapping" the relay makes any difference, then you have a bad relay, new or not (unless your wiring is not holding together).

Grounding the green wire should make the fan run (with a good relay in place). It will stop running after key is turned off (may take a few seconds for it to stop).

Project86B4Z

its an 85 sports coupe with a stock 2.8 v6 mpfi...i just added the 92 gfx to it and plan on dropping in a 350 in a few weeks

camaronewbie

I see where I'm confused - austinthirdgen.org doesn't list the 2.8l V6 wiring diags in 1985, so I assumed there wasn't one.

BUT - none of the 2.8l V6 wiring diags for 1986 or 1987 show a fan switch in the head - I still think the ECM has total fan control and there is no fan switch on a 2.8l motor. I don't even see it in the wiring diags for the 3.1 motor either. I don't think V6 cars have a fan switch. And I have confidence in the austinthirdgen.org diags - they were copied straight out of the GM service manuals.

But it sounds like your issue is with your fan relay and/or it's connector.

Maverick H1L

iTrader: (8)

The 2.8 was available in ALL 3rd gens to 1989... It was made the base engine when GM dropped the 2.5 in 86. 1982-early 85 had the E2SE carb, and was switched to fuel injection in mid 85 with better crank and cylinder heads.

The problem with Austin ThirdGen is that they use the wiring diagrams taken from a Chilton's manual or the like... And most of us know they're really good ... The link I posted above has scans from the 1986 GM service manual (the TGO home page link to the 85 scans is dead), which is identical to my 1987 FSM except it's in color (and maybe because mine is possibly a b&w reprint?). Oh, and as I remember from visiting the 85 scans site a long time ago, they're the same.

Project86B4Z

so is the coolant fan switch (on the diagram) the single terminal sensor that was on the driver side head because that controls my temp gauge now...and if not how about that sensor next to the cts on the intake that has a blue block on it?

Maverick H1L

iTrader: (8)

Nope... Driver's side switch is GAUGE... Passenger's side, in the rear, by the lifting eye, is FAN... The blue thing in the intake is for the seventh injector, leave it alone as you can't really replace it... It's the cold start injector temperature switch. The thing you're looking for has a mushroom-shaped head on it with the connector removed, and the connector looks just like the brake warning light switch on the proportioning valve except it's a different color with a green wire in it and removes the same (squeeze and pull). And no, I don't have a pic because I haven't had one since 2004...

Project86B4Z

that's what i'm beginning to believe...its gotta be ecm related since jumping aldl doesn't turn it on...wonder how much it could run me to have it rewired correctly back to its stock form...

Maverick H1L

iTrader: (8)

Well, where does the green wire come from that's disconnected at the relay? Disconnect the fan switch in the passenger's side head and find out. Since there are 2 green wires going to the same terminal in the relay, it's either the fan switch wire or the ECM control wire, and this test finds out. FYI, I've had wires break at the relay terminals, and they're a lot of fun to put back together again . At least, if one is in good shape but the other is broken off, you can splice the wires together and have it work again.

Project86B4Z

Well i guess its back to the drawing board on this one...thanks guys...

Maverick H1L

iTrader: (8)

Well, as long as you don't want to try to fix it by following suggestions on how to find out what works and what doesn't...

Project86B4Z

It's was a bad relay and wire fixing it Friday