CTS problem from hell, please help!
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA
if the ecm is the issue just do this, tap into the ground feed wire from the ecm at the relay and run a single wire to a sensor like this and it will cure your problem, works like a charm on my 1990 and I had the same issues as you no matter what the fans would not run. just screw a sensor like this between your #1 & #3 plug there is a threaded in plug there remove it and your problem will cease to exist. I used a 228 on 212 off switch and my car can cool down in about 25-30 seconds.
Team Owner
Joined: Jan 2003
Posts: 20,316
Likes: 246
From: Summerland B.C. Canada
http://members.shaw.ca/corvette86/Co...%20Control.pdf
Thread Starter
Pro
Joined: Feb 2005
Posts: 560
Likes: 0
From: Hamilton New Jersey
There is battery voltage in and out, red is in, so your link is most likely good. You need to be concerned with 12 volts for the coil side of relay(fuse),12 volts out and a ground from ECM. Maybe it's just the fan fuse.
http://members.shaw.ca/corvette86/Co...%20Control.pdf
http://members.shaw.ca/corvette86/Co...%20Control.pdf
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
No dedicated Fan Fuse for this Year. Switch side (ignition power) is from the ECM fuse (Blue) and driven (grounded - Green/White) by the ECM. Once the Relay is activated, fan power is from the Fusible Link (always hot - Red) - to fan (Black/Red).
Link is good if it has voltage on the Red - Check Relay by jumpering to green/white to ground. Check Black/Red to fan if it doesn't run.
Link is good if it has voltage on the Red - Check Relay by jumpering to green/white to ground. Check Black/Red to fan if it doesn't run.
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA
1989 350 tpi. I'm having an extremely annoying problem with my coolant temp sensor, I'm not sure where to go from here, maybe someone can point me in the right direction. The problem is basically this, the reading is always too low (voltage reading too high). It operates in the proper way, that is voltage starts out high and slowly lowers as the car heats up, the problem is it never gets low enough for the fans to operate. At 240 degrees the voltage reading is around 1.5 volts. I've tried several different sensors, all with the same results. I tested the wires from the connector to the ecu, they both ohm out at .4 volts which leads me to believe they are ok. I've tried a different ecu (with the same prom), still same results. The only thing I can think of is maybe I have a crappy ground somewhere, does anyone know where the ground is located? Is there anything else that could be the problem? This thing is driving me nuts, I just want to be able to drive the piece of **** without it overheating and bogging off idle..
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Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
There isn't one - just a Circuit 150 which has quite a few devices/ ground wires, not all of which are grounded at the same point. Unfortunately, relying on the Service Manual Schematics can lead to confusion. The ECM section shows the Main Cooling fan ground as being a Circuit 150 Ground. The 8A Schematic shows it as a Circuit 151 ground. The A/C Fan Pressure Switch is a 150 Circuit ground, and if it's open, the Main Fan would be running at all times. If you simply want the Main Fan grounding point, it's on the left front crossmember. The '89 grounds are fairly simple - crossmember and framerails for lights & fans and non ECM functions. Engine/Transmission and frame rail (backup) for Battery and ECM. Forward interior left and right cowls. Rear behind the behind the passenger seat. Gas tank also has a secondary ground - tank to frame (to keep static electricity from causing a fire when you fill up).
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Scanning would help you compare the CTS with your Display. Disconnecting the Display Sender (in the Head between 6 & 8) should give you Lo - grounding the Lead about 300. You could also try a new Sender - just be specific about it as most Discounters/Suppliers will bring out a CTS. If you can, take the old Sender with you to the Parts Store.
Thread Starter
Pro
Joined: Feb 2005
Posts: 560
Likes: 0
From: Hamilton New Jersey
Scanning would help you compare the CTS with your Display. Disconnecting the Display Sender (in the Head between 6 & 8) should give you Lo - grounding the Lead about 300. You could also try a new Sender - just be specific about it as most Discounters/Suppliers will bring out a CTS. If you can, take the old Sender with you to the Parts Store.
Thread Starter
Pro
Joined: Feb 2005
Posts: 560
Likes: 0
From: Hamilton New Jersey
Yeah the ground wire was corroded inside the insulation, there was a small pin hole in it that water must have gotten into. The bog was fixed with a the new CTS. Turned out I had to different problems that occured at the same time which really threw me a curve ball.
Safety Car
Joined: Oct 2008
Posts: 4,689
Likes: 4
From: Yucaipa CA
Yeah the ground wire was corroded inside the insulation, there was a small pin hole in it that water must have gotten into. The bog was fixed with a the new CTS. Turned out I had to different problems that occured at the same time which really threw me a curve ball.