Temp Gauge Not Working

[retrotrip]

Hi there!

I bought a 1987 Ranger last month and am IN LOVE. She's perfect, except, the temperature gauge on the dash doesn't work. It's always pointing to the lowest possible "C" position.

Before I get ripped off by one of the local shops (not a lot of options in this small town), can someone please recommend a potential cause of this malfunction? If there's a wire or sensor I can check with a few basic tools, I'd like to pursue that first.

Thank you in advance!

 

[RonD]

Welcome to TRS

Yes, the the Temp SENDER on the engine is the usual problem, and it is easy to test and replace.

But.................need to know what engine you have to tell you where to look for it

1987 had 3 engine options
2.0l 4 cylinder
2.3l 4 cylinder, gasoline
2.9l V6

Rare was the 2.3l Turbo-Diesel engine in a 1987, last year for these

 

[retrotrip]

Re: RonD

Thank you!

Mine is a 2.9 V6

2.9l V6

 

[RonD]

Drawing here: https://www.2carpros.com/images/question_images/181315/original.jpg

The red arrow is NOT the one you want, that is the temp SENSOR, only used by the fuel injection computer

Look to the right, you will see the temp SENDER, it only has 1 wire connected

Get a jumper wire and Ground one end of that wire, Battery Negative if wire is long enough
Pull off the 1 wire on the SENDER, and Ground that wire using the jumper wire
Go into the cab and turn on the key, watch the temp gauge
If temp needle goes up to HOT then wire and Temp Gauge are working fine
Replace SENDER.

If needle doesn't move then wire from sender or gauge itself is the problem, but that is rarely the case.

Auto parts store will always give you a SENSOR first time around, so stress Temp SENDER "for the gauge" when you ask for the part
Take it out of the box and make sure it just has 1 connection, sensors always have 2 connectors

When installing a SENDER leave the bottom few threads BARE metal, sender needs a good ground to the engine to work properly

 

[retrotrip]

Hi! Thank you very much for your thorough directions and help! Turns out, the sender needs replacing. I picked up the part today and will install tomorrow. The part has a white coating around the bottom half of the threads (on the engine-end, not the connector end). Do I leave the white coating on or peel it off before installing?

Thank you again! You just saved me at least $100

 

[GR8RYD]

The white coating is most likely Teflon tape or some type of thread sealer. You should leave it on.

 

[RonD]

Yes, the white coating is OK, don't add anything else