Analog temp signal to dash - Page 2 - ZR-1 Net Registry Forums

Jetjock · 12-13-2010

I looked in the service manual and found a section that discusses the CCM sending out the signal to the digital gauge and actually has it in the CCM twice. Still can't find the info about the analog gauge other that there is an "air core" gauge for coolant temp. The description of the sensor indicates that it is a thermocouple device which can go either way depending on the need.

-=Jeff=- · 12-13-2010

did not get a chance to look tonight.. will check tomorrow.. sorry

gbrtng · 12-15-2010

Quote:

Originally Posted by -=Jeff=-

I will check tonight, but I am pretty sure the one sensor is the analog and the other is ECM & digital

All the engine sensors are analog except for the on/off switches. Any analog to digital conversion is done in the ECM.

Jetjock · 12-15-2010

Hey Glenn, I figured that you would know. How you doing?

-=Jeff=- · 12-15-2010

Quote:

Originally Posted by gbrtng

All the engine sensors are analog except for the on/off switches. Any analog to digital conversion is done in the ECM.

Yes, I should have clarified.. one analog sensor feeds the gauge

the other analog sensor feeds the ECM and CCM ( digital gauge)

Paul Workman · 12-16-2010

In short, power comes from the "HOT IN RUN" circuit, and goes to the gauge. The gauge is a three-pole bridge; one is the 12-volt power input, one is ground (G201), and the third goes to the temp sensor - a variable resistor - which is grounded in the IH housing.(1)

If I'm not mistaken, of the two sensors, the one that has the single wire with the slide-on connector is the sensor you're looking for.

With a VOM, and the switch on, you should get a voltage reading between the connector and ground. With the connector removed from the sensor, you will get a higher reading than with the connector attached to sensor. Sorry, I don't have data on what that reading should be - maybe someone has their plenum off and could check that out for us?

Anyway, No voltage at the connector when detached from the sensor (ignition switch in "ON" position) means a connection or the fuse (which would affect all the analog gauges, BTW) is bad. The voltage will drop when connected to the sensor, but it should not go to ZERO, unless the sensor is bad (shorted).

Hope this helps,

P.
_______________________

(1) FSM, Ch 8, pp 8A-80-0

John Boothby · 12-16-2010

Since you changed the sensor, it could be a bad one. Chances are though, the connection is bad. Common when working under the plenum and the secondary plumbing. Ask me how I know?

Jetjock · 12-16-2010

While this isn't the first time that I have changed the sensor, this is the first time that the analog gauge stopped working. The connector itself distegrated in my hands while I was trying to put it back on. It's entirely possible that the connector fell off the new sensor. The analog gauge doesn't show anything; it just sits at the middle of the gauge and doesn't move. I'm thinking that it could have shorted out to ground or something happened to the gauge. Don't know at this point but the other sensor has a much better connector to it. New sensors all round. We have to pull the plenum again which is no big deal to put in new spark plug wires. Didn't have them the first time.

Paul Workman · 12-16-2010

Quote:

Originally Posted by Jetjock

While this isn't the first time that I have changed the sensor, this is the first time that the analog gauge stopped working. The connector itself distegrated in my hands while I was trying to put it back on. It's entirely possible that the connector fell off the new sensor. The analog gauge doesn't show anything; it just sits at the middle of the gauge and doesn't move. I'm thinking that it could have shorted out to ground or something happened to the gauge. Don't know at this point but the other sensor has a much better connector to it. New sensors all round. We have to pull the plenum again which is no big deal to put in new spark plug wires. Didn't have them the first time.

OOOOOoooh! You are having too much fun! This thread makes me chuckle. NO, I'm not laughing at you, but memories are still so fresh! I see I'm not the only one that can open a can o' worms!

Good luck!

P.

Jetjock · 12-16-2010

The LT5 motor that I am working on isn't my car. It belongs to a guy that decided to buy it and doesn't know anything about the car. He did something that he shouldn't have and it stopped running. So I helped him out by replacing the starter, coil packs, spark plugs, injectors and coolant hoses. The motor had been worked on before and various things moved around so it got interesting. The engine started right up and we checked the coolant. Then a couple of things happened. The analog gauge did not work and the service engine soon light came on. The digital temp was only reading 203 degrees at the time. There could be one or two items for that but I checked the codes before and nothing came up. He wants to put new plug wires in which is okay by me but time consuming. The Z hasn't had a lot of attention in the past five years so these things keep cropping up. The car is a 92 and a dark red color of which only 17 were made. It has multiple issues with clutch, brakes, headlight motors, etc.

12-13-2010	#11
Jetjock Join Date: Mar 2008 Location: Auburn, KY Posts: 557	Re: Analog temp signal to dash I looked in the service manual and found a section that discusses the CCM sending out the signal to the digital gauge and actually has it in the CCM twice. Still can't find the info about the analog gauge other that there is an "air core" gauge for coolant temp. The description of the sensor indicates that it is a thermocouple device which can go either way depending on the need.

12-13-2010	#12
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,157	Re: Analog temp signal to dash did not get a chance to look tonight.. will check tomorrow.. sorry __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - Flowmaster Cats - Borla Catback Late Model IH - Plenum Coilovers - 4.10s Shelby Series 1 - Wilwood Brakes Custom Interior NCM Lifetime Member #978

12-15-2010	#14
Jetjock Join Date: Mar 2008 Location: Auburn, KY Posts: 557	Re: Analog temp signal to dash Hey Glenn, I figured that you would know. How you doing?

12-16-2010	#16
Paul Workman Join Date: Nov 2007 Location: Squires (near Ava MO in the Mark Twain N'tl Forest) - Missouri Posts: 6,466	Re: Analog temp signal to dash In short, power comes from the "HOT IN RUN" circuit, and goes to the gauge. The gauge is a three-pole bridge; one is the 12-volt power input, one is ground (G201), and the third goes to the temp sensor - a variable resistor - which is grounded in the IH housing.(1) If I'm not mistaken, of the two sensors, the one that has the single wire with the slide-on connector is the sensor you're looking for. With a VOM, and the switch on, you should get a voltage reading between the connector and ground. With the connector removed from the sensor, you will get a higher reading than with the connector attached to sensor. Sorry, I don't have data on what that reading should be - maybe someone has their plenum off and could check that out for us? Anyway, No voltage at the connector when detached from the sensor (ignition switch in "ON" position) means a connection or the fuse (which would affect all the analog gauges, BTW) is bad. The voltage will drop when connected to the sensor, but it should not go to ZERO, unless the sensor is bad (shorted). Hope this helps, P. _______________________ (1) FSM, Ch 8, pp 8A-80-0 Last edited by Paul Workman; 12-16-2010 at 07:39 AM.

12-16-2010	#17
John Boothby Join Date: Jul 2005 Location: Las Vegas, Nevada Posts: 775	Re: Analog temp signal to dash Since you changed the sensor, it could be a bad one. Chances are though, the connection is bad. Common when working under the plenum and the secondary plumbing. Ask me how I know?

12-16-2010	#18
Jetjock Join Date: Mar 2008 Location: Auburn, KY Posts: 557	Re: Analog temp signal to dash While this isn't the first time that I have changed the sensor, this is the first time that the analog gauge stopped working. The connector itself distegrated in my hands while I was trying to put it back on. It's entirely possible that the connector fell off the new sensor. The analog gauge doesn't show anything; it just sits at the middle of the gauge and doesn't move. I'm thinking that it could have shorted out to ground or something happened to the gauge. Don't know at this point but the other sensor has a much better connector to it. New sensors all round. We have to pull the plenum again which is no big deal to put in new spark plug wires. Didn't have them the first time.

12-16-2010	#20
Jetjock Join Date: Mar 2008 Location: Auburn, KY Posts: 557	Re: Analog temp signal to dash The LT5 motor that I am working on isn't my car. It belongs to a guy that decided to buy it and doesn't know anything about the car. He did something that he shouldn't have and it stopped running. So I helped him out by replacing the starter, coil packs, spark plugs, injectors and coolant hoses. The motor had been worked on before and various things moved around so it got interesting. The engine started right up and we checked the coolant. Then a couple of things happened. The analog gauge did not work and the service engine soon light came on. The digital temp was only reading 203 degrees at the time. There could be one or two items for that but I checked the codes before and nothing came up. He wants to put new plug wires in which is okay by me but time consuming. The Z hasn't had a lot of attention in the past five years so these things keep cropping up. The car is a 92 and a dark red color of which only 17 were made. It has multiple issues with clutch, brakes, headlight motors, etc. Last edited by Jetjock; 12-16-2010 at 02:49 PM.