|
|
Register To Post |
| patgizz | cooling fans not working | ||
|
Senior Guru
 
|
ok i got the 91 running
#1 i'm a tard - i jumped the gun and thought my engine was toast, but i had some electrical issues that were getting enough juice to the starter to click it over and make it look like the engine was frozen, but not enough to actually kick it over even with a fresh battery. so i fixed that. my wiring underhood is getting sad though and has seen way better days. the heat has taken its toll for 18 years/115k miles and things were beginning to not work, work erratically, and finally i lost the injector wiring somewhere along the way. the main bundle behind the engine by the heater box is in bad shape. the wires are brittle and the covering loom just fell apart in my hands. #2 in the interest of ever being able to drive my car this summer, and in the case of being totally poor since i bought a house and am getting married in 3 weeks, i made the executive decision to sell the superram and install a single plane intake and a carb instead of putting a whole new engine harness in the car. everything functions as it should - with the exception of the cooling fans and converter lockup. i assumed to need a stand alone lockup kit because of the lack of TPS so that is no big deal. but my cooling fans are not coming on - at all. the temp sensor is installed and the wires to it should be good as it was one of the things functioning properly prior to the swap - but i won't rule out something happening in the time since as things went downhill pretty quickly. (i wonder if the wiring fried the ecm and that is why i lost injector pulse but that is not a huge issue right now) what all do i need to check for ? i could always get an aftermarket controller with a seperate sending unit and run them that way but i prefer to just make them work with the stock setup if it is possible other than the fans and lockup - i need to pull 12v ign underhood somewhere for my electric choke hookup - any convenient sources for that besides my refusal to splice into the coil wire? the ass dyno tells me it's faster than it was with the TPI and right on par with the superram. |
||
Posted on: 2009/8/2 18:09
|
|||
 Transfer
|
 
|
||
| iCorvette | Re: cooling fans not working | ||
|
Senior Guru
|
bypass the temp switch by # 1 and 3, the one in front is for the gauge and is a sending unit, the one near feeds the ecm.
if you don't have a front auxiliary fan, you may not have the switch at 1 and 3, if after that the fan runs, it the switching, if it don't it's the fan motor i have an 89, yours could be different.my guess is yours is an LTx someone else could correct me if I AM ALL WRONG, but this is my recollection |
||
Posted on: 2009/8/2 18:25
|
|||
|
_________________
|
|||
|
Transfer
|
|
||
| BillH | Re: cooling fans not working | ||
|
The Stig Moderator
 
|
Quote:
LT1's started in 1992. Both fans in an LT1 are controlled by relays on the right radiator shrould. Pat, I think the L98s also have relays for the fan(s). You need to find where they are and which wire is the activation ground. The ECM should signal the fan to come on and ground that wire. You can test the fan circuit by finding that wire in the relay plug and grounding it by splicing into it (Make sure you have the correct wire). |
||
Posted on: 2009/8/2 19:51
|
|||
|
_________________
Every man dies but not every man lives. |
|||
|
Transfer
|
|
||
| 1Fast04Vert | Re: cooling fans not working | ||
|
Elite Guru
 
|
LT1's started in 1992. Both fans in an LT1 are controlled by relays on the right radiator shrould.
quote] Actually there are two relays on the LT1, but on the left or drivers's side of the shroud. |
||
Posted on: 2009/8/2 19:56
|
|||
|
_________________
2004 Vert. 475hp. Built by Vengeance Racing |
|||
|
Transfer
|
|
||
| BillH | Re: cooling fans not working | ||
|
The Stig Moderator
|
Quote:
I musta been standing on top of the radiator shroud looking down.  Some days, I don't know my right from my left. LT1: Attach file:  IMGP0548.jpg (0.00 KB) |
||
Posted on: 2009/8/2 20:01
|
|||
|
_________________
Every man dies but not every man lives. |
|||
|
Transfer
|
|
||
| patgizz | Re: cooling fans not working | ||
|
Senior Guru
|
yeah same relays as the 91.
i'll look to the ground test first to see if that makes them come on. i'll pull out the FSM to see which wire it is. |
||
Posted on: 2009/8/3 0:09
|
|||
|
Transfer
|
|
||
| vetteoz | Re: cooling fans not working | ||
|
Senior Guru
 |
Quote:
iCorvette wrote: i have an 89, yours could be different Do not pass go. All C4's from '90 on had ECM control of both fans; no temp switch in head as on earlier setups. Quote: iCorvette wrote: the one in front is for the gauge ... the one near feeds the ecm. Wrong again. As it comes from the fctory ; On '89 the one and only sensor at front is the coolant temp sensor for the ECM (CTS). If there are 2 units then it is a a early manifold with cold start injector switch (CSI) The temp gauge sender unit is in the pass side head between #6 & 8 |
||
Posted on: 2009/8/3 0:31
|
|||
|
Transfer
|
|
||
| Woodstock | Re: cooling fans not working | ||
|
Senior Guru
|
To check the fans, you could simply short A+B at the ALDL diagnostic port, just like pulling trouble codes. In diagnostic mode the fan should kick right on. You could swap relays, both are the same, in case one is toasted.
|
||
Posted on: 2009/8/3 1:56
|
|||
|
_________________
91 convertible |
|||
|
Transfer
|
|
||
| patgizz | Re: cooling fans not working | ||
|
Senior Guru
|
ok guru geniuses
i found some time in my hectic schedule(cause we had to quit early today due to storming) and plugged my little OBD1 tester in - ignition on both fans kick on. where do i look now - temp sensor? i forget the test method - something like 1600 ohms @ room remp and it's good? i have known good ones in my electrical box that i've tested before putting in there if i need one. i picked up a hayden aftermarket dual adjustable fan controller if i need it- but i've needed one on my belair for a while so if i do not have to use it on the vette i've got a home for it. |
||
Posted on: 2009/8/10 21:16
|
|||
|
Transfer
|
|
||
| Woodstock | Re: cooling fans not working | ||
|
Senior Guru
|
Now that we know the fans are working and you got time on your hands, we like to keep you busy
 The sensor you can check by measuring resistance, it's not an easy task though, when the sensor is still installed. 100°F is 1600 ohm, 70°F 3400 ohm, you do the math in between. To test function of the wiring, you could short the plug that goes into the sensor. The fan should again kick right on. That would confirm good wiring and a good ECM. |
||
Posted on: 2009/8/11 0:06
|
|||
|
_________________
91 convertible |
|||
|
Transfer
|
|
||
| patgizz | Re: cooling fans not working | ||
|
Senior Guru
|
80.5* gives me 2600 ohms(pays to have a high end multimeter with a temperature probe)
ignition on, jumping the sensor wires in the plug does nothing. |
||
Posted on: 2009/8/11 0:44
|
|||
|
Transfer
|
|
||
| 1Fast04Vert | Re: cooling fans not working | ||
|
Elite Guru
|
What happens when you trun on the AC?
|
||
Posted on: 2009/8/11 2:18
|
|||
|
_________________
2004 Vert. 475hp. Built by Vengeance Racing |
|||
|
Transfer
|
|
||
| vetteoz | Re: cooling fans not working | ||
|
Senior Guru
|
Quote:
So that means everything electrically is working fine , you are not getting a signal from the ECM to turn the fans on. WHICH TEMP SENSOR ARE YOU CHECKING? The gauge one or the ECM one (CTS ). If you do not have the CTS installed and connected (was at front of intake under TB) then there is nothing to tell the ECM what temp engine is at! The temp gauge runs off it's own sensor , not from the one the ECM uses for it calcs. Just buy one of these as used in the '86 - '89 cars for the aux fan; install in the drv side head and use that to operate the fan relays (goes to ground at switch ) This is the lower ON temp one , other temps are available http://www.zip-corvette.com/Zip/produ ... 266BE45B7A5564FF3BFCC3988 |
||
Posted on: 2009/8/11 4:58
|
|||
|
Transfer
|
|
||
| patgizz | Re: cooling fans not working | ||
|
Senior Guru
|
checking the CTS - not the gauge sending unit. it's installed in the new intake in same location as factory.
|
||
Posted on: 2009/8/11 13:15
|
|||
|
Transfer
|
|
||
| MK 82 | Re: cooling fans not working | ||
|
Senior Guru
|
Partially correct. 95 and 96 use three relays to allow the fans to run in tandem in lo or hi speed.
Quote:
|
||
Posted on: 2009/8/11 18:25
|
|||
|
_________________
96 CE Roadster LT4 |
|||
|
Transfer
|
|
||
| Woodstock | Re: cooling fans not working | ||
|
Senior Guru
|
Quote:
ignition on, jumping the sensor wires in the plug does nothing. Wow, that's a new one for me. Never heard of an ECM going south with those symptoms. Got anyone around to swap ECMs? Last test to be certain, check the yellow wire for 5V reference signal and the black wire for ground. |
||
Posted on: 2009/8/12 11:05
|
|||
|
_________________
91 convertible |
|||
|
Transfer
|
|
||
| BrianCunningham | Re: cooling fans not working | ||
|
Senior Guru
|
Have you tried hooking the fans up direct to see if they're working?
|
||
Posted on: 2009/8/12 13:33
|
|||
|
_________________
Polo Green 95 LT1 6-spd http://mysite.verizon.net/vzevcp74/ 383 LT1/Vortech Supercharger/AFR heads/Rod end suspension/Penske-Hardbar dual rate coilovers/Wilwood 6pot brakes NCCC Governor: http://BayStateCorvetteClub.com |
|||
|
Transfer
|
|
||
| patgizz | Re: cooling fans not working | ||
|
Senior Guru
|
can turn both on with the aldl brian
i'll check for reference signal and ground at the cts plug and see what happens when i turn on the AC - does it matter if it is empty? i had to remove the compressor to pull the valve covers to get the superram off. |
||
Posted on: 2009/8/14 1:44
|
|||
|
Transfer
|
|
||
| 1Fast04Vert | Re: cooling fans not working | ||
|
Elite Guru
|
Quote:
An empty system won't matter. The pressure switch should keep the compressor clutch from engaging, but the fans should still come on. |
||
Posted on: 2009/8/14 2:32
|
|||
|
_________________
2004 Vert. 475hp. Built by Vengeance Racing |
|||
|
Transfer
|
|
||
| Matatk | Re: cooling fans not working | ||
|
Webmaster
 
|
Quote:
Not sure on the 91, but on the 89 if there is not enough head pressure in the a/c the fan won't kick on, I was dealing with this issue myself. Matthew |
||
Posted on: 2009/8/14 12:45
|
|||
|
_________________
2002 EBM convertible, Magnusson supercharger, cam, headers, etc. 1989 Corvette...RIP |
|||
|
Transfer
|
|
||
| 1Fast04Vert | Re: cooling fans not working | ||
|
Elite Guru
|
Quote:
Matt, you are probably correct as the low pressure switch does communicate with the 'puter. Possible to 'paperclip' the switch to make it think there is pressure? The basic idea of my suggestion is it might be a very easy/simple way to see if the ECM is communicating with the fans. |
||
Posted on: 2009/8/14 13:16
|
|||
|
_________________
2004 Vert. 475hp. Built by Vengeance Racing |
|||
|
Transfer
|
|
||
| pappyfreebird | Re: cooling fans not working | ||
|
Senior Guru
|
same here on a 84..was pressure switch in comp (the one that was recalled n changed to pipe by firewall) mine musta slipped past them daze..but ony one fan too in 84
|
||
Posted on: 2009/8/14 14:02
|
|||
|
Transfer
|
|
||
| patgizz | Re: cooling fans not working | ||
|
Senior Guru
|
ok
got the 5 volt reference signal at the CTS plug nothing when i turn the AC on unless there are any better ideas i'm installing the aftermarket fan controller tomorrow so i can drive my car. |
||
Posted on: 2009/8/15 1:39
|
|||
|
Transfer
|
|
||
You can view topic.
You cannot start a new topic.
You cannot reply to posts.
You cannot edit your posts.
You cannot delete your posts.
You cannot add new polls.
You cannot vote in polls.
You cannot attach files to posts.
You cannot post without approval.
|
|