coolant temperature sensor
Thread Starter
Heel & Toe
Joined: Jun 2006
Posts: 19
Likes: 0
From: Garnet Valley PA
coolant temperature sensor
Can anyone help with a question about the CTS in my 1988 corvette L98.
I would like to test the sensor, I am having problems with the coolant fans not turning on.
thanks for your help
I would like to test the sensor, I am having problems with the coolant fans not turning on.
thanks for your help
Le Mans Master
Joined: Aug 2000
Posts: 8,838
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From: Australia
Race Director
Joined: Apr 2002
Posts: 10,036
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From: Anaheim CA
The coolant temperature sensor that the ECM uses is located on the front of the intake manifold. You can measure its resistance according to this chart:
I have found that the low coolant light can come on if the radiator cap is bad. It is caused by the coolant not flowing in and out of the overflow tank the way it ought to.
I have found that the low coolant light can come on if the radiator cap is bad. It is caused by the coolant not flowing in and out of the overflow tank the way it ought to.
Thread Starter
Heel & Toe
Joined: Jun 2006
Posts: 19
Likes: 0
From: Garnet Valley PA
Thank you everyone, I checked the CTS temp in accordance with the ohms on the chart and found everything to match up. I also have burped the system already and I do have 12V on the main relay wire. The fan fuse also checked out okay which led me to the ECM.
While testing connections there I found that that the tan/wht wire from the relays does NOT go to the ECM, instead it goes through the C207 connector which ultimately leads up under the dash.
I believe my problem lies in this C207 connector not making the right connections. If anyone has a pinout for a 1988 corvette it would be greatly appreciated. Thanks.
While testing connections there I found that that the tan/wht wire from the relays does NOT go to the ECM, instead it goes through the C207 connector which ultimately leads up under the dash.
I believe my problem lies in this C207 connector not making the right connections. If anyone has a pinout for a 1988 corvette it would be greatly appreciated. Thanks.
Thread Starter
Heel & Toe
Joined: Jun 2006
Posts: 19
Likes: 0
From: Garnet Valley PA
The wiring layout of the C207 is as follows:
(A) - BROWN
(B) - BLACK
(C) - BRN/WHT
(D) - TAN/WHT
(E) - WHT/BLK
(F) - PNK/BLK
(G) - BLACK
(H) - TAN/BLK
(J) - ORANGE
(K) - BROWN
(L) - NOT USED
(M) - BLKWHT
(N) - ORG/BLK
(P) - PURPLE
(R) - PPL/WHT
I just need to know each wire's function to fully resolve this issue.
(A) - BROWN
(B) - BLACK
(C) - BRN/WHT
(D) - TAN/WHT
(E) - WHT/BLK
(F) - PNK/BLK
(G) - BLACK
(H) - TAN/BLK
(J) - ORANGE
(K) - BROWN
(L) - NOT USED
(M) - BLKWHT
(N) - ORG/BLK
(P) - PURPLE
(R) - PPL/WHT
I just need to know each wire's function to fully resolve this issue.
Team Owner
Joined: Jan 2003
Posts: 20,277
Likes: 236
From: Summerland B.C. Canada
[QUOTE=smeds;1581327266]The fan fuse also checked out okay which led me to the ECM.
While testing connections there I found that that the tan/wht wire from the relays does NOT go to the ECM, instead it goes through the C207 connector which ultimately leads up under the dash.(/quote)
My info is from my 86, there is no tan/white wire on fan relay and I don' t recall 88 having one either.
Are you sure you are testing the main fan relay ?
While testing connections there I found that that the tan/wht wire from the relays does NOT go to the ECM, instead it goes through the C207 connector which ultimately leads up under the dash.(/quote)
My info is from my 86, there is no tan/white wire on fan relay and I don' t recall 88 having one either.
Are you sure you are testing the main fan relay ?
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Thread Starter
Heel & Toe
Joined: Jun 2006
Posts: 19
Likes: 0
From: Garnet Valley PA
Yes, I have tested both and both check out though the TAN/WHT wire in position D on the relay routes to the C207 connector.
My problem is that I do not have a drawing identifying which each wire on the C207 corresponds to and therefore cannot establish that the opposite end of the C207 is mating correctly.
My problem is that I do not have a drawing identifying which each wire on the C207 corresponds to and therefore cannot establish that the opposite end of the C207 is mating correctly.
Team Owner
Joined: Jan 2003
Posts: 20,277
Likes: 236
From: Summerland B.C. Canada
Yes, I have tested both and both check out though the TAN/WHT wire in position D on the relay routes to the C207 connector.
My problem is that I do not have a drawing identifying which each wire on the C207 corresponds to and therefore cannot establish that the opposite end of the C207 is mating correctly.
My problem is that I do not have a drawing identifying which each wire on the C207 corresponds to and therefore cannot establish that the opposite end of the C207 is mating correctly.
Where are the 2 relays you are testing ?
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
The main fan relay is located on the rear of the LH fender well under the master cylinder. It's pin-outs are:
A - Blk/Red -> coolant fan
E - Red -> fusable link D
D - Dk Blu -> C100 -> C.Fan Fuse
F - Dk Grn/Wht -> C100 -> C237 -> ECM C1
BTW, C207 connects the Ign Sw: C1 to Fuse Block: A/C Fuse & C Fan Fuse & Pwr Wdo Circuit Breaker.
A - Blk/Red -> coolant fan
E - Red -> fusable link D
D - Dk Blu -> C100 -> C.Fan Fuse
F - Dk Grn/Wht -> C100 -> C237 -> ECM C1
BTW, C207 connects the Ign Sw: C1 to Fuse Block: A/C Fuse & C Fan Fuse & Pwr Wdo Circuit Breaker.
Last edited by 65Z01; Jul 17, 2012 at 06:07 AM.
Thread Starter
Heel & Toe
Joined: Jun 2006
Posts: 19
Likes: 0
From: Garnet Valley PA
Yes, I am certain both relays are perfectly functional.
The issue I believe I am having is that the wire running through the C207 is not reaching the fuse block under the dash. If i could find out what each wire in the C207 corresponds to I believe I can resolve the issue quickly.
The C207 is a part of the wiring harness that runs through the firewall to the ECM, however it does not go to the ECM it branches off and runs under the dash, several wires including the one for the fan relay go through this circuit to the fuse block.
The issue I believe I am having is that the wire running through the C207 is not reaching the fuse block under the dash. If i could find out what each wire in the C207 corresponds to I believe I can resolve the issue quickly.
The C207 is a part of the wiring harness that runs through the firewall to the ECM, however it does not go to the ECM it branches off and runs under the dash, several wires including the one for the fan relay go through this circuit to the fuse block.
Team Owner
Joined: Jan 2003
Posts: 20,277
Likes: 236
From: Summerland B.C. Canada
I'll ask again, where are the 2 relays your are testing ?
65Z01 posted the wire colors for 88, there is NO tan/white wire on cooling fan relays, yet you continue with telling us the relays are perfectly functional and have a tan/white wire going into C207.
65Z01 also posted the route of ECM wire to relay "F" - Dk Grn/Wht -> C100 -> C237 -> ECM C1
He also posted that " C207 connects the Ign Sw: C1 to Fuse Block: A/C Fuse & C Fan Fuse & Pwr Wdo Circuit Breaker".
Wake up and smell the coffee
65Z01 posted the wire colors for 88, there is NO tan/white wire on cooling fan relays, yet you continue with telling us the relays are perfectly functional and have a tan/white wire going into C207.
65Z01 also posted the route of ECM wire to relay "F" - Dk Grn/Wht -> C100 -> C237 -> ECM C1
He also posted that " C207 connects the Ign Sw: C1 to Fuse Block: A/C Fuse & C Fan Fuse & Pwr Wdo Circuit Breaker".
Wake up and smell the coffee