NissanDiesel Forums

Hi everybody,

This weekend I was under the hood tightening the water pump/alternator belt which made the chirping sound go away (yes the belt was loose, not worn out). When I was done I noticed that the temperature gauge is no longer working. I'm assuming that I bumped something while I was under there but I'm not sure where to start troubleshooting. There appear to be two sensors in the thermostat housing one with a single wire and one with two. I can't recall off hand which one is for the temperature gauge or what the other one does. I checked the wires for soundness and for dirty connections but I'm not sure what to do next. Is there a simple way to test that the sensor is working?

On an only slightly-related theoretical note, do you think that if a person were to overheat an SD22 without knowing that the oil pressure would drop enough that the DPC would save your ass before major damage occurred? I have not done this and wouldn't count it but this situation made me wonder if it would work like that. Thanks for the advice, you guys are the best.

EvergreenSD wrote:There appear to be two sensors in the thermostat housing one with a single wire and one with two.

Single wire is for the gauge.

Is there a simple way to test that the sensor is working?

Simple way takes TWO people.

One person inside, looks at temp gauge. Key ON. Other person under hood briefly -- and I mean briefly -- grounds the single wire. About one second. Do not ground it for longer than three seconds, or the gauge may be damaged.

When the single wire is grounded, the temp gauge's needle should begin rapidly swinging up toward 'H'. If not, look for wiring issues, gauge, or gauge voltage regulator (integrated into the instrument cluster).

Harder way is to use your FSM and an ohmmeter and test the resistance of the sender's terminal to ground, use the chart to ascertain what the resistance should be. They do not typically go bad on the Nissan. But the terminal collects corrosion, and the wire's terminal looses its spring tension. Philip has a post on this topic, if you use Search you may find it.

do you think that if a person were to overheat an SD22 without knowing, that the oil pressure would drop enough that the DPC would save your ass before major damage occurred?

No, I don't.

EvergreenSD wrote:SNIP- There appear to be two sensors in the thermostat housing one with a single wire and one with two. I can't recall off hand which one is for the temperature gauge or what the other one does.

The single wire connects to your coolant temperature. That single female terminal must fit on FIRMLY ... not just the plastic tube around the terminal. Also make sure (about 6-8 inches away) another male/femal connector is secure

The twin conection is for your AutoGlow temperature.

evergreenSD wrote:On an only slightly-related theoretical note, do you think that if a person were to overheat an SD22 without knowing that the oil pressure would drop enough that the DPC would save your ass before major damage occurred?

It's possible if ... you had very thin engine oil, and/or very over heated oil (300°F), and idling low (ie 500 RPM). In that situation, oil pressure could drop under 10 psi which is the Oil Pressure Switch point.

Thnks so much for your help guys. It was just some corrosion on the connector between the sensor and the wire. I hadn't noticed that there was a connection in that spot. Your timely advice really helped me clear up this issue with a minimum of hassle. Much appreciated.