65 Gauges not working
Thread Starter
Joined: Apr 2015
Posts: 12
From: CO
65 Gauges not working
Hello! I am new to the forum and about to get me restored 65 Mustang 289 back on the road. However, I cannot get the Fuel and Temp gauges to operate correctly. I have done the IVR test - pulse at end of sensor line. I get the gauges to move when grounding, (with sensor connected), and everything else works fine. I have analyzed the back of the instrument cluster and cleaned all connections. Wiring and fuses seem fine. Both sending units were replaced new. Just replaced temp sending unit again and no change. I don't know what else to check? Any ideas from you experts out there? Thank you!
6th Gear Member
Joined: Oct 2006
Posts: 6,417
From: Cork, Ireland
if pulse test works fine, then as a next test I'd disconnect wire from temp sensor and ground it on motor block with ignition on. if that causes high temp reading, the sensor needs replacing.
if it does not read high, then next thing is to try to put that cable directly to battery minus. if that causes to read high temp, you have problems with engine ground
if you can't get it to read hot this way i'd try as next step to connect the gauge side that is not attached to IVR straight to ground. latest then you should get hot reading.
on more thing to check, do instrument lights come on when you have ignition and lights on?
let us know the results, that should help to isolate it further
if it does not read high, then next thing is to try to put that cable directly to battery minus. if that causes to read high temp, you have problems with engine ground
if you can't get it to read hot this way i'd try as next step to connect the gauge side that is not attached to IVR straight to ground. latest then you should get hot reading.
on more thing to check, do instrument lights come on when you have ignition and lights on?
let us know the results, that should help to isolate it further
Thread Starter
Joined: Apr 2015
Posts: 12
From: CO
Thank you! I now have the instrument cluster out and it seems the IVR is putting out constant voltage from both sides. Both gauges work when grounded at sensor end. There is no pulse - just constant at sensor end. Both Fuel and Temp gauge are acting this way. When grounded - gauge moves. I also seem to have a problem with the regulator under the hood as the alternator was still trying to turn the last time I turned off the car. The battery seems to also not be charging. I noticed the regulator under the hood had not been grounded until recently - so maybe I have burned that up? I will also check the alternator and make sure it is wired correctly. All lights, horn and instrument panel lights work as well. Do I need to change out IVR and voltage regulator under hood? Thank you so much!
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