86 305tpi
#1
Member
Thread Starter
Join Date: Apr 2003
Location: Frankenmuth, MI
Posts: 121
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91z
Engine: 350 vortec
Transmission: built 700r4
Axle/Gears: 373
86 305tpi
I have an 86 iroc with a 305 tpi and it has a single cooling fan that runs continuously. I unplugged all the a/c sensors. I ohmed out the relay and it checks out ok. I've replaced the fan switch below the throttle body. I put an ecm in it but it still stays running. I can't find any shorts. Thoughts?
#2
Senior Member
Join Date: Sep 2006
Location: San Antonio, Tx
Posts: 568
Likes: 0
Received 7 Likes
on
6 Posts
Car: 1988 Camaro IROC-Z
Engine: LB9 (305 TPI)
Transmission: 700R4
Axle/Gears: 2.73 Positraction
Re: 86 305tpi
With the key on check the relay for proper operation. With the fan on you should be able to unplug it and hear it click. Then reconnect and if clicks right away you have a 12V short on the low current supply side (relay coil is energized at all times, closing the switch on the high current side). If it doesn't click but the fan comes on you have a 12V short on the high current supply side. If it's the low current side work backwards from the relay plug to find the crossed circuit and isolate. If it's on the high current side work backwards from the fan to find the crossed circuit and isolate.
#3
Member
Thread Starter
Join Date: Apr 2003
Location: Frankenmuth, MI
Posts: 121
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91z
Engine: 350 vortec
Transmission: built 700r4
Axle/Gears: 373
Re: 86 305tpi
I'm curious, how many ohms should I be seeing when the pcm grounds the relay? .2 or so.
#4
Member
Thread Starter
Join Date: Apr 2003
Location: Frankenmuth, MI
Posts: 121
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91z
Engine: 350 vortec
Transmission: built 700r4
Axle/Gears: 373
Re: 86 305tpi
Update; I missed the low pressure cut-off switch when I was unplugging the rest of the a/c items. Unplugged it, the fan turned off. Derrr
#7
Member
Thread Starter
Join Date: Apr 2003
Location: Frankenmuth, MI
Posts: 121
Likes: 0
Received 0 Likes
on
0 Posts
Car: 91z
Engine: 350 vortec
Transmission: built 700r4
Axle/Gears: 373
Re: 86 305tpi
Well I replaced the switch but it didn't fix it. Every time I unplug it, it turns off. Every schematic and description and operation on all-data, contradicts itself. I'm at a loss now. I don't have a Tech1 to scan it either. The ECM is definitely grounding the relay. Why? I don't know. Things I've checked: Control head is properly grounded. Refrigerant level ok, relay not shorted, wiring to fan not shorted, replaced coolant temp sensor under TB, wiring to sensor checked out ok. I replaced the ecm, still turns on. It has a hyperchip in it, maybe that went bad??? I don't have a switch in the head between the #6 & 8 plug like I've read everywhere else. All data says its in the a/c line and the schematic agees b/c the wiring that goes to the sensor is spot on.
Thread
Thread Starter
Forum
Replies
Last Post
Stell1579
Aftermarket Product Review
2
10-11-2000 10:47 PM