Coolant temp 299 degrees upon start up...
Thread Starter
Safety Car
Joined: Dec 2004
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From: Poop land
Coolant temp 299 degrees upon start up...
That didn't seem right when I just started the car about an hour after I let it sit in the rain. I checked the CTS, unplugged it and plugged it back and it still says 299 degrees. Where does the digidash get its coolant temp input from??
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Safety Car
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From: Poop land
Well, it doesn't look like the insulation is broken. Could some wire in the harness be shorting itself to ground? What about an open in the circuit? How do I go about checking the wire up in there? Could the rain water be shorting something out?
I just hate seeing that 299 degrees for the coolant temp because I really would have no idea what the coolant temp really is.
At least it still runs ok though...
I just hate seeing that 299 degrees for the coolant temp because I really would have no idea what the coolant temp really is.
At least it still runs ok though...
Le Mans Master
Joined: Apr 2005
Posts: 8,077
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From: Scarborough ONTARIO
Oh same problem here, actually thats fake temp b/c cTS is either loose or no contact with wire, finally changed that CTS between #1 and #3 cyl in head. CTS is not cheap 40 bucks. Problem soved after CTS replacement.
Thread Starter
Safety Car
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From: Poop land
Originally Posted by sami85L98
Oh same problem here, actually thats fake temp b/c cTS is either loose or no contact with wire, finally changed that CTS between #1 and #3 cyl in head. CTS is not cheap 40 bucks. Problem soved after CTS replacement.
I have a feeling that a short would cause it to read 299 and an open in the circuit would cause it to say Lo. Correct me if I'm wrong...
Does anyone have an ohm chart for this sensor?
Well, car still runs fine with a "299 degree" reading right on the digidash, so I can't be overheating.
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Safety Car
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From: Poop land
Originally Posted by 2nd2SEX
Turn on the car. Let it idle for 10 minutes. Remove the radiator cap and stick your finger in there. What temp is that??
Originally Posted by zr1fred
Disconnect the wire and check the guage, then short the wire to ground and check again. Make sure you have water in it, and that it really isn't hot!
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Thread Starter
Safety Car
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From: Poop land
Originally Posted by Hot Rod 90
did you check for codes? 14 relates ot a bad coolant temp sensor.
I hope its just the sensor thats bad and not wiring. Tracing shorts in the harness is a nightmare.
Le Mans Master
Joined: Apr 2005
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From: Scarborough ONTARIO
Originally Posted by kopbet89c4
I think this is strictly only for the digidash input.
I hope its just the sensor thats bad and not wiring. Tracing shorts in the harness is a nightmare.
I hope its just the sensor thats bad and not wiring. Tracing shorts in the harness is a nightmare.
Make sure u emptied radiator or atleast suck a gallon or 2 or fill radiator and bleed, burp radiator after putting back new sensor. Expect lot of coolant from that CTS location once u removed it, use anti sieze on thread's of CTS. Goodluck.
Le Mans Master
Joined: Jan 2003
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From: Santa Maria CA
Originally Posted by zr1fred
Disconnect the wire and check the guage, then short the wire to ground and check again. Make sure you have water in it, and that it really isn't hot!
Since guage shows hot when motor is cold, the sender circuit might be shorted.
Pull the single wire off the sensor. Go look at the temp reading now.
If the reading on the cluster now shows cold, the wiring to the sender is good. Replace the sender.
http://www.parts123.com/parts123/yb....Z5Z5Z50000050F
If the reading remains hot with it unplugged, there is a short somewhere along the sender wire back to the instrument cluster.
Trace the wiring.
Last edited by 86PACER; Aug 12, 2006 at 03:54 AM.
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From: Poop land
Originally Posted by 86PACER
You do that when the temp display shows cold when the engine is actually hot. His symptom is the opposite.
Since guage shows hot when motor is cold, the sender circuit might be shorted.
Pull the single wire off the sensor. Go look at the temp reading now.
If the reading on the cluster now shows cold, the wiring to the sender is good. Replace the sender.
http://www.parts123.com/parts123/yb....Z5Z5Z50000050F
If the reading remains hot with it unplugged, there is a short somewhere along the sender wire back to the instrument cluster.
Trace the wiring.
Since guage shows hot when motor is cold, the sender circuit might be shorted.
Pull the single wire off the sensor. Go look at the temp reading now.
If the reading on the cluster now shows cold, the wiring to the sender is good. Replace the sender.
http://www.parts123.com/parts123/yb....Z5Z5Z50000050F
If the reading remains hot with it unplugged, there is a short somewhere along the sender wire back to the instrument cluster.
Trace the wiring.
Race Director
Joined: Sep 2000
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From: The Top of Utah
Here is the acid test. With the engine off, turn the ignition key to "On". Observe the gauge. Remove the wire from the sensor and recheck the gauge. Now, ground that wire. Check the gauge again. If the gauge reads 299 one way and "Low" the other, between being disconnected and grounded, then the sensor is bad. The Ohm readings for the sensor at different temps is in your FSM. If, when you ground the wire, the auxiliary fan starts running, you have proved the wiring for the aux fan, the relay, the fan motor, and me as working and being correct as to the locations of the sensors. If so, move from the fan switch to the other side of the car and perform the same checks on the REAL gauge sending unit in the right head between the #6 and #8 spark plugs.
RACE ON!!!
RACE ON!!!
Melting Slicks
Joined: Aug 1999
Posts: 2,240
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From: Baltimore, MD USA
Originally Posted by kopbet89c4
I have a feeling that a short would cause it to read 299 and an open in the circuit would cause it to say Lo. Correct me if I'm wrong...
Does anyone have an ohm chart for this sensor?
Does anyone have an ohm chart for this sensor?
On your 89 the sender for the Gage is between spark plug 6 and 8. It has a single spade lug with a Dark Green wire.
Here's the resistance values and what the gage should show.
1.6K ohms or higher should read LO
1.06K ohms=110F +-6F
254 ohms=180F +- 6F
135 ohms=220F +-6F
75 ohms=261F +-6F
Unplug the Dark Green wire from the sender. Turn the ignition on. Coolant display shoud read LO. If it does the wire and gage are probably good and the sender is bad.
If the display still shows 299 the wire is shorted or the Gage/Dash cluster is bad. With the Dark Green wire unplugged, use an ohm meter and measure the resistance of the sender from the spade lug to ground.
Last edited by Hooked on Vettes; Aug 12, 2006 at 01:19 PM.