Temp gauge and Tachometer don't work

[Buckner99]

Hello, I've had this 1984 Nissan 720 for quite a while now. I've done the timing chain replacement as well as the timing cover replacement, spark plugs, wires, full tune up. new water pump, starter, everything on the front of the block has been replaced. went through my Chilton book multiple times. The one thing i have a question about is my gauge cluster. Ever since I've owned this truck my temp gauge, and my tachometer do not work. My fuel gauge works as well as speedometer, oil pressure, battery (oil and battery are by the shifter) My sensor light is on but I do not know how to read OBD1 Vehicles. most people on here affiliate tachometer and temp gauge with the fuel gauge. In this case I'm assuming that my gauge cluster is bad. Id like to know where the CTS is located so I can check it out. I've torn the dash off to fix a bunch of shorts and loose wires, but everything going to the cluster is all intact. Everything with the engine and performance is fixed, and now I am trying to work on cosmetics. thanks.

[Lockleaf]

Your truck is not obd 1.  The sensor light is not a check engine light.  Its on a mileage based timer.  You simply s disconnect and leave it disconnected.  That is actually how it's designed.

 

To test temp gauge, disconnect the wire from the temp sensor and ground the wire directly to the engine block..  Temp gauge should peg to full hot.  If the temp gauge goes to hot with that solid grounding, then your gauge works fine.

 

Corrosion between wire and temp sensor in engine is common.  Brush both clean.  Sensor could also be bad.  Lots of info online about testing temp sensors.

 

CTS?

 

Tach requires a resistor to operate. It may be the resistor is bad or gone.  Resistor is in the harness, in engine bay, drivers side fender.

[datzenmike]

The SENSOR lamp is a reminder to replace the O₂ sensor in the exhaust.

[Buckner99]

22 minutes ago, Lockleaf said:

Your truck is not obd 1.  The sensor light is not a check engine light.  Its on a mileage based timer.  You simply s disconnect and leave it disconnected.  That is actually how it's designed.

 

To test temp gauge, disconnect the wire from the temp sensor and ground the wire directly to the engine block..  Temp gauge should peg to full hot.  If the temp gauge goes to hot with that solid grounding, then your gauge works fine.

 

Corrosion between wire and temp sensor in engine is common.  Brush both clean.  Sensor could also be bad.  Lots of info online about testing temp sensors.

 

CTS?

 

Tach requires a resistor to operate. It may be the resistor is bad or gone.  Resistor is in the harness, in engine bay, drivers side fender.

I feel very uneducated, and  I appreciate the response. now all the wiring on my driver side fender had been messed with when I got the truck. It was all wire nutted together so I bought a cole hersee terminal block and distributed the wires out so it was a lot more clean looking. If you knew the color of the wire going to the resistor that would be very helpful. I will be doing alot more research about it. not that its an issue, I shift by sound. but adjusting the carb and such is difficult with not knowing  what RPM the truck is at. Thank you. 

[Buckner99]

18 minutes ago, datzenmike said:

The SENSOR lamp is a reminder to replace the O₂ sensor in the exhaust.

Thank you for that info. alot I dont know about these trucks. Bought it about 6 months ago, and have been fixing things left and right. very thankful I found this forum. Its saved me a lot of work so far. 

[datzenmike]

White /Blue stripe to the resister from the coil -,  and Black/Blue from the resistor to the gauge.

 

Resister

 

 

[Buckner99]

2 minutes ago, datzenmike said:

White /Blue stripe to the resister from the coil -,  and Black/Blue from the resistor to the gauge.

 

Resister

 

 

Thank you so much! I just found the wire going to my temp sensor completely disconnected from the connector. touched it to ground, gauge needle started going towards hot. spliced a new spade connector on the wire and plugged it in. so if its a bad resistor, are they possible to get on rockauto or something like that? I would probably just visit my local junkyard.

[datzenmike]

I doubt it but any 2,2K ohm resister will do.

[Buckner99]

 

Just now, datzenmike said:

I doubt it but any 2,2K ohm resister will do.

 is there anyway I could bypass it? 

[datzenmike]

No. It's there for a reason. I cut one open and it's 1/4 or 1/2 watt 2200 ohm or 2.2K ohm.

 

https://www.amazon.ca/Projects-10EP5122K20-2-2k-Resistors-Pack/dp/B0185FKB2S/ref=sr_1_5?dchild=1&keywords=2200+ohm+resistor&qid=1607893595&sr=8-5

 

 

 

[Buckner99]

thanks. when I pulled the resistor off there was a lot of dirt and stuff between the connections. gonna grab one from the junkyard and if it doesnt work im assuming i have a bad gauge

 

[datzenmike]

The original is taped up in the wire harness and just looks like a lump. '83 and up are over to the rear of the battery. Previous years are over by the coils.

[Buckner99]

ya, I read it wrong when it said driver side. I thought you meant passenger by the battery. But I found it on the driver side. And mines a 84.. by the coils.