So the cars been warming up recently, no biggie looked and found the primary fan doesn't come on at all. Interesting, so I jump the a and b pin on the DLC and it does come on. I swapped relays with the secondary fan that does work as normal, and it still doesn't work. So I'm basically sitting at the fact that the pcm isn't requesting the primary fan at all.....Temp gauge reads normal so I'm at one of two places.....either there's a wiring issue from the pcm to the relay or the pcm isn't asking for the fan to be on which would lead me to believe it's the sensor in the WP.....Only thing is the secondary fan comes on.....I'm stumped anyone have any ideas?

 

Does your car have an AIR Pump? My 97 had this problem 2 weeks ago and it ended up being that the AIR Pump was shorting out and I was blowing my fuse for the Fans. I pulled my relay for the pump and haven't had a problem since. I also have the manual fan override switch installed and I could power the fans for High speed but when I would go to Low speed I would pop the fuse. This doesn't sound like your problem but maybe it might be worth looking into.

 

It does still have the air pump on it.....it's fully stock for now....I'm working on getting the LT's put on, but I kinda wanna figure out this fan issue first....I'll have to double check the fuses and go from there I guess.

 

bump, still looking for a possible cause.....jumping the DLC turns both on so the wiring is good, the relay has been swapped and that shows they're both good, so I'm stumped. Obviously the sensor for the PCM is functioning since the secondary fan comes on.....anyone have any ideas....ShBox are you out there???

 

Do they both come on high speed with the AC on?

 

it's a 93 so they are single speed fans, but if I jump the a and b pins on the ALDL it turns both of them on.

 

Yea..forgot about that. Maybe one of the PCM terminals for it went out. I don't know what else would cause that..pretty much it's similar to the rest of the cars that this happens to. Mine did it and the wiring was perfect, a friend of mine's did it and his wiring was good. It's a fluke thing..

 

It's just really agitating since the car really heats up...to the bottom of the red...before it starts to cool off again, and I really don't want to warp any cyl. heads

 

You may have to install Manual Switches.

Do those 2-Relay setups run high-speed only? Do you know a little about wiring, I can send you the diagram for the 3-Relay Low-High speed.

 

yes unfortunately the 93's run one speed, all or nothing. I can work my way aroundd the wiring and I've been checking out shbox's stuff, but I'm still trying to figure out what the heck is going on......I'm sure it'll be something stupid once I figure it out....I really don't want to install a switch, but I suppose I may have to.....

 

My 96' runs hot because my second fan comes on every now and then. It will run hot and the second won't kick on sometimes so i think i'm gonna order that SLP manual fan switch. That should fix the prob. huh guy!?

 

Probably. I have the Autozone Fan Switch..2 of them..and they work fine.

I also got my LS PCM re-tuned for my new 408, we went in there and I found why my Fans were't working for the new setup..they were set to come on at 280*

I think they were disabled cause I hadn't wired them in yet, now they are wired in so they will work with the PCM..set to come one at 200/210, shut off at 185/195.

Hopefully they work with the Manual Switches on the same circuit.

 

You'll need to monitor it with a scanner, see if the fan request is being made. If made and the fan does not come on, check to see if the ground is being sent out by the computer to the relay. It's just a matter of tracking along the normal path of operation of the circuit.

 

Similiar problem which I haven't chased down myself. Both mine come on vs the secondary only. Just started recently and even w/ the manual fan switch where I can control both fans seperately...they'll both kick on when I hit the low switch or high switch. Can't complain really since they both do the job twice as fast in terms of cooling but it's really a pain trying to figure out.

 

Hey SRZ, I do believe that I read on here that both fans come on at High and Low speed. The difference is low speed gives it a 6 volt power source and when high speed is selected it bumps it up to 12 volts. I believe SHBOX has that on his Tech Page.

 

On the dual speed fans, they run in series on low and parallel on high. The power source is still 12v.

 

"Probably. I have the Autozone Fan Switch..2 of them..and they work fine."

The Merv.... are those fan switches set up simular to the SLP switches. I've never heard of them and was wondering because I'm gonna go with one or the other.

 

I was just saying I bought 2 Switches at Autozone..

I don't know how the SLP ones are setup..I just spliced them into the Control Wires going to the Fuse Box, ran them to the Interior, installed the Switch and grounded the other side.

It works for me..

 

Oh I see. lol Ok The Merv. I may just do that then. Thanks again!

 

Now you see..lol

You know what wires you need to splice into?