Discussion:
Function of sensor in radiator, 1988 2.8 MPI
(too old to reply)
ednaboopadoop
2013-09-09 07:05:48 UTC
Permalink
1988 2.8 Cavalier Z24 has overheating issues. Coolant fan doesn't kick on at high temp, but will run strong when a jumper wire is connected from battery positive. Someome put another relay on it but problem persisted, unplugged the new relay and saw that old, gummy dielectric grease from the harness receptacle got all over the prongs of the new relay. Blasted both clean with electronics cleaner as best as I could, but still no fan at high temp. I notice the car has a single-wire sensor plugged into the front of the radiator, and I'm guessing that is what sends the signal to the ECM to start the cooling fan -- correct? It also uses the two-wire CTS mounted on the engine, which I presume feeds to the ECM to interface with the other sensor readings for optimal emissions and power, etc. Is the single-wire sensor likely the culprit? Also, what is the best way to clean out a multi-prong plug receptacle (like the fan relay here) to get rid of all that old dielectric grease -- seems VERY hard to get it clean.
Geoff Welsh
2013-09-10 02:36:53 UTC
Permalink
Post by ednaboopadoop
1988 2.8 Cavalier Z24 has overheating issues. Coolant fan doesn't
kick on at high temp, but will run strong when a jumper wire is
connected from battery positive. Someome put another relay on it but
problem persisted, unplugged the new relay and saw that old, gummy
dielectric grease from the harness receptacle got all over the prongs
of the new relay. Blasted both clean with electronics cleaner as
best as I could, but still no fan at high temp. I notice the car has
a single-wire sensor plugged into the front of the radiator, and I'm
guessing that is what sends the signal to the ECM to start the
cooling fan -- correct? It also uses the two-wire CTS mounted on the
engine, which I presume feeds to the ECM to interface with the other
sensor readings for optimal emissions and power, etc. Is the
single-wire sensor likely the culprit? Also, what is the best way to
clean out a multi-prong plug receptacle (like the fan relay here) to
get rid of all that old dielectric grease -- seems VERY hard to get
it clean.
best i recall:

single wire sensor is for gage (or idiot-light).

Two wire sensor is for ECM. ECM controls fan relay.

You need a scan tool that can stream data on that ancient beast to see
if the ECM is "seeing" the proper temp from the sensor.

I would use brake cleaner and compressed air to un-goop a relay socket.

GW
PeterD
2013-09-12 11:37:12 UTC
Permalink
...and I'm guessing that is what sends ...
Suggestion: stop guessing and get the service manual so you know what
you are working with.
--
I'm never going to grow up.
ednaboopadoop
2013-09-13 14:22:22 UTC
Permalink
Post by PeterD
...and I'm guessing that is what sends ...
Suggestion: stop guessing and get the service manual so you know what
you are working with.
I couldn't find one, which is why I posted -- but I since did find one on eBay and it should be here today. BTW -- wouldn't your reply apply to pretty much absolutely any post on here? ("Get a service manual and figure it out yourself")
Post by PeterD
--
I'm never going to grow up.
ednaboopadoop
2013-09-19 17:48:31 UTC
Permalink
Post by ednaboopadoop
1988 2.8 Cavalier Z24 has overheating issues. Coolant fan doesn't kick on at high temp, but will run strong when a jumper wire is connected from battery positive. Someome put another relay on it but problem persisted, unplugged the new relay and saw that old, gummy dielectric grease from the harness receptacle got all over the prongs of the new relay. Blasted both clean with electronics cleaner as best as I could, but still no fan at high temp. I notice the car has a single-wire sensor plugged into the front of the radiator, and I'm guessing that is what sends the signal to the ECM to start the cooling fan -- correct? It also uses the two-wire CTS mounted on the engine, which I presume feeds to the ECM to interface with the other sensor readings for optimal emissions and power, etc. Is the single-wire sensor likely the culprit? Also, what is the best way to clean out a multi-prong plug receptacle (like the fan relay here) to get rid of all that old dielectric grease -- seems VERY hard to get it clean.
The single-wire sensor in the radiator runs the low-cooland idiot light. The problem with the fan turned out to be the fusible link, which hooks up to the battery junction block on the firewall directly behind the master cylinder. Replaced fusible link with an in-line fuse holder.
Ashton Crusher
2013-09-21 17:07:27 UTC
Permalink
On Thu, 19 Sep 2013 10:48:31 -0700 (PDT), ednaboopadoop
Post by ednaboopadoop
Post by ednaboopadoop
1988 2.8 Cavalier Z24 has overheating issues. Coolant fan doesn't kick on at high temp, but will run strong when a jumper wire is connected from battery positive. Someome put another relay on it but problem persisted, unplugged the new relay and saw that old, gummy dielectric grease from the harness receptacle got all over the prongs of the new relay. Blasted both clean with electronics cleaner as best as I could, but still no fan at high temp. I notice the car has a single-wire sensor plugged into the front of the radiator, and I'm guessing that is what sends the signal to the ECM to start the cooling fan -- correct? It also uses the two-wire CTS mounted on the engine, which I presume feeds to the ECM to interface with the other sensor readings for optimal emissions and power, etc. Is the single-wire sensor likely the culprit? Also, what is the best way to clean out a multi-prong plug receptacle (like the fan relay here) to get rid of all that old dielectric grease --
seems
Post by ednaboopadoop
VERY hard to get it clean.
The single-wire sensor in the radiator runs the low-cooland idiot light. The problem with the fan turned out to be the fusible link, which hooks up to the battery junction block on the firewall directly behind the master cylinder. Replaced fusible link with an in-line fuse holder.
Thanks for posting the solution. I wish more people would.
ednaboopadoop
2013-09-24 01:29:43 UTC
Permalink
Post by ednaboopadoop
Post by ednaboopadoop
1988 2.8 Cavalier Z24 has overheating issues. Coolant fan doesn't kick on at high temp, but will run strong when a jumper wire is connected from battery positive. Someome put another relay on it but problem persisted, unplugged the new relay and saw that old, gummy dielectric grease from the harness receptacle got all over the prongs of the new relay. Blasted both clean with electronics cleaner as best as I could, but still no fan at high temp. I notice the car has a single-wire sensor plugged into the front of the radiator, and I'm guessing that is what sends the signal to the ECM to start the cooling fan -- correct? It also uses the two-wire CTS mounted on the engine, which I presume feeds to the ECM to interface with the other sensor readings for optimal emissions and power, etc. Is the single-wire sensor likely the culprit? Also, what is the best way to clean out a multi-prong plug receptacle (like the fan relay here) to get rid of all that old dielectric grease -- seems VERY hard to get it clean.
The single-wire sensor in the radiator runs the low-cooland idiot light. The problem with the fan turned out to be the fusible link, which hooks up to the battery junction block on the firewall directly behind the master cylinder. Replaced fusible link with an in-line fuse holder.
The 20-amp fuse in the new fuse holder popped immediately when the fan was energized. The fusible link said "20" on it, so I presume that meant 20 amps was the max that circuit could draw. Will a powerful motor like a radiator fan pop a 20 amp fuse during start-up, where a 20 amp fusible link would not melt
during the same period? I chose the fuse-holder to avoid the hassle of changing the fusible link in the event of future overload.
Geoff Welsh
2013-09-24 03:10:09 UTC
Permalink
Post by ednaboopadoop
On Monday, September 9, 2013 2:05:48 AM UTC-5, ednaboopadoop
Post by ednaboopadoop
1988 2.8 Cavalier Z24 has overheating issues. Coolant fan
doesn't kick on at high temp, but will run strong when a jumper
wire is connected from battery positive. Someome put another
relay on it but problem persisted, unplugged the new relay and
saw that old, gummy dielectric grease from the harness receptacle
got all over the prongs of the new relay. Blasted both clean
with electronics cleaner as best as I could, but still no fan at
high temp. I notice the car has a single-wire sensor plugged
into the front of the radiator, and I'm guessing that is what
sends the signal to the ECM to start the cooling fan -- correct?
It also uses the two-wire CTS mounted on the engine, which I
presume feeds to the ECM to interface with the other sensor
readings for optimal emissions and power, etc. Is the
single-wire sensor likely the culprit? Also, what is the best
way to clean out a multi-prong plug receptacle (like the fan
relay here) to get rid of all that old dielectric grease -- seems
VERY hard to get it clean.
The single-wire sensor in the radiator runs the low-cooland idiot
light. The problem with the fan turned out to be the fusible link,
which hooks up to the battery junction block on the firewall
directly behind the master cylinder. Replaced fusible link with an
in-line fuse holder.
The 20-amp fuse in the new fuse holder popped immediately when the
fan was energized. The fusible link said "20" on it, so I presume
that meant 20 amps was the max that circuit could draw. Will a
powerful motor like a radiator fan pop a 20 amp fuse during start-up,
where a 20 amp fusible link would not melt during the same period? I
chose the fuse-holder to avoid the hassle of changing the fusible
link in the event of future overload.
From what you have said, the fan motor is bad. It should never pull
that much current, and a new one won't.

GW
Ashton Crusher
2013-09-24 06:33:39 UTC
Permalink
On Mon, 23 Sep 2013 18:29:43 -0700 (PDT), ednaboopadoop
Post by ednaboopadoop
Post by ednaboopadoop
Post by ednaboopadoop
1988 2.8 Cavalier Z24 has overheating issues. Coolant fan doesn't kick on at high temp, but will run strong when a jumper wire is connected from battery positive. Someome put another relay on it but problem persisted, unplugged the new relay and saw that old, gummy dielectric grease from the harness receptacle got all over the prongs of the new relay. Blasted both clean with electronics cleaner as best as I could, but still no fan at high temp. I notice the car has a single-wire sensor plugged into the front of the radiator, and I'm guessing that is what sends the signal to the ECM to start the cooling fan -- correct? It also uses the two-wire CTS mounted on the engine, which I presume feeds to the ECM to interface with the other sensor readings for optimal emissions and power, etc. Is the single-wire sensor likely the culprit? Also, what is the best way to clean out a multi-prong plug receptacle (like the fan relay here) to get rid of all that old dielectric grease --
seems VERY hard to get it clean.
Post by ednaboopadoop
The single-wire sensor in the radiator runs the low-cooland idiot light. The problem with the fan turned out to be the fusible link, which hooks up to the battery junction block on the firewall directly behind the master cylinder. Replaced fusible link with an in-line fuse holder.
The 20-amp fuse in the new fuse holder popped immediately when the fan was energized. The fusible link said "20" on it, so I presume that meant 20 amps was the max that circuit could draw. Will a powerful motor like a radiator fan pop a 20 amp fuse during start-up, where a 20 amp fusible link would not melt
during the same period? I chose the fuse-holder to avoid the hassle of changing the fusible link in the event of future overload.
Fuses are intended to blow FAST. Fusible links are intended to be
much more forgiving of short term overloads. Like the other poster
said, it could very well be the fan motor is bad. I'd get another
fusible link and see how long it lasts. You can get them at any auto
parts store.

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