85 TPI Coolant Temp Sensor
Thread Starter
Junior Member
Joined: Apr 2016
Posts: 1
Likes: 0
85 TPI Coolant Temp Sensor
Greetings to all. Been lurking around here for a while but this will be my first post.
I have an 85 Trans Am TPI and over the weekend I replaced my coolant temp sensor and the sender. Install went about as straight forward as it could, but during the test drive my fan would not turn on. Gage was getting close to the red (260*) so I pulled over and shut it off. I jumped the diagnostic port so that the fan would kick on as I waited, and it did. I got home and double checked my connection and everything is fine. With the engine off and ignition on in park, the fan kicked on in my driveway.
My guess is a faulty replacement switch. I've been looking at the Hypertech 4028 or the Jet 60600 and then doing a 180* thermostat. The Jet only says for years 1986-92 with dual fans, and I can't find the Hypertech for sale by anyone reputable.
Any help would be greatly appreciated. Been searching this forum non stop lately for everything.
I have an 85 Trans Am TPI and over the weekend I replaced my coolant temp sensor and the sender. Install went about as straight forward as it could, but during the test drive my fan would not turn on. Gage was getting close to the red (260*) so I pulled over and shut it off. I jumped the diagnostic port so that the fan would kick on as I waited, and it did. I got home and double checked my connection and everything is fine. With the engine off and ignition on in park, the fan kicked on in my driveway.
My guess is a faulty replacement switch. I've been looking at the Hypertech 4028 or the Jet 60600 and then doing a 180* thermostat. The Jet only says for years 1986-92 with dual fans, and I can't find the Hypertech for sale by anyone reputable.
Any help would be greatly appreciated. Been searching this forum non stop lately for everything.
Joined: Nov 2010
Posts: 5,892
Likes: 84
From: Mantua NJ
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: 85 TPI Coolant Temp Sensor
Before you go and start going crazy you should invest in one of these
http://www.harborfreight.com/non-con...ing-61894.html
Our gauges are notorious for reading wrong.
Our fans don't go on till the temp hits 235 and it's not uncommon for the fans to be a good 20 degrees.
See what happens when you turn the AC on,that should turn the fans on.
http://www.harborfreight.com/non-con...ing-61894.html
Our gauges are notorious for reading wrong.
Our fans don't go on till the temp hits 235 and it's not uncommon for the fans to be a good 20 degrees.
See what happens when you turn the AC on,that should turn the fans on.
Last edited by mantaguy; Aug 1, 2016 at 08:22 PM.
Junior Member
Joined: Oct 2012
Posts: 30
Likes: 0
From: Pittsburgh
Car: 85 Z28
Engine: 305 TPI (LB9)
Transmission: 700r4
Axle/Gears: 3.23
Re: 85 TPI Coolant Temp Sensor
Unrelated to your question, sorry. How many and what things did you remove to get at the cts? I don't think I can get in there without removing some things.
Joined: Aug 1999
Posts: 5,259
Likes: 460
From: RI
Car: 1984 Camaro Berlinetta
Engine: LT1
Transmission: T56 6-speed
Axle/Gears: 4.11 LS1 Rear End
Re: 85 TPI Coolant Temp Sensor
I'm pretty sure the 85 TPI cooling fan is controlled by the ECM. The Hypertech 4028 or the Jet 60600 is used on duel fan, some carb, and TBI cars to control the cooling fan. So; installing either of those temp sending units will not help you in any way. ( if the car is still "Stock" ! )
IIRC the CTS ( mounted on the front of the TPI Intake Manifold ) is what tells the ECM the coolant temps, and the ECM will send a signal to the fan relay when the temp reaches about 235 degrees. Here's the 85TPI fan schematic:
IIRC the CTS ( mounted on the front of the TPI Intake Manifold ) is what tells the ECM the coolant temps, and the ECM will send a signal to the fan relay when the temp reaches about 235 degrees. Here's the 85TPI fan schematic:
Joined: Nov 2010
Posts: 5,892
Likes: 84
From: Mantua NJ
Car: 1 Owner 1986 TA with a WS6 package
Engine: 5.0 EFI
Transmission: THM700R4
Axle/Gears: 277 Posi Speedo
Re: 85 TPI Coolant Temp Sensor
I'm pretty sure the 85 TPI cooling fan is controlled by the ECM. The Hypertech 4028 or the Jet 60600 is used on duel fan, some carb, and TBI cars to control the cooling fan. So; installing either of those temp sending units will not help you in any way. ( if the car is still "Stock" ! )
IIRC the CTS ( mounted on the front of the TPI Intake Manifold ) is what tells the ECM the coolant temps, and the ECM will send a signal to the fan relay when the temp reaches about 235 degrees. Here's the 85TPI fan schematic:
IIRC the CTS ( mounted on the front of the TPI Intake Manifold ) is what tells the ECM the coolant temps, and the ECM will send a signal to the fan relay when the temp reaches about 235 degrees. Here's the 85TPI fan schematic:
Thread
Thread Starter
Forum
Replies
Last Post
notrabies
Electronics
5
Jul 29, 2016 09:39 PM
Thirdgen89GTA
History / Originality
5
Mar 29, 2016 11:28 AM