1989 Ford Ranger Temp Gauge

Tiny
BELLEAUT
  • MEMBER
  • 1989 FORD RANGER
  • 2.9L
  • 6 CYL
  • 2WD
  • MANUAL
  • 60,000 MILES
I have replaced the sending unit because my temp gauge does not work and I am getting code 21 and 42. 21 is missing temp signal. I tested the gauge wire by grounding the wire to make the gauge read hot. New sending unit and old one did not make the needle move at all.

Could it be the sensor?

I am getting mixed messages about where the sending VS the sensor is. I believe the sending unit has one post on top with one wire pressed onto it. (Replaced it with no change on the gauge)

The sensor is bigger and has a gray wire clip on top of it. Looks like two wires running in and out of it. Does this sensor have anything to do with the gauge? Is there a test?
I am at a loss. I have read so many posts on so many different sites that I cannot tell how many sensors I should be looking for. I cannot find anything on the back of the engine.
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Saturday, April 18th, 2015 AT 9:40 AM

6 Replies

Tiny
HMAC300
  • EXPERT
It's a two wire connector with a gry /yellow wire and blk/white wire the black white goes back to gauge. Code s21 may be a bad ecm or poor connection for code 42 check fuel pressure key on engine off should be 30-45 psi if higher it may be pressure regulator or leaking injectors.
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Saturday, April 18th, 2015 AT 10:30 AM
Tiny
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Thank you for the feed back. When I ground the single pole sensor the gauge goes all the way to Hot. That tells me the single pole sensor goes to the gauge also. Am I wrong on that? I will check the fuel pressure next.
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Saturday, April 18th, 2015 AT 11:26 AM
Tiny
BELLEAUT
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Fuel pressure test had bad results. The key on engine off produced 0 pressure. I could hear the fuel pump but no pressure.
When I started the engine it rose to 30.
When I turned the engine off it started to drop right away. I then turned the key back on but did not start it. The pressure jumped a little bit but still continued to fall.
How to figure out where the leak is?

The trunk only has 60,000 miles on it and it has sat for a long time. I have put a little less than 200 miles driving it home and trying to tune it up.

When I take the large rubber hose off of the intake manifold there is a strong smell of gas, I do not know if this will tell me that it is the fuel regulator or a leaking fuel injector.

When I replaced the plugs the plugs that came from the same side as the regulator were much darker. The three from the other side looked normal. Lighter burn color. Not black.
Thanks again.
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Saturday, April 18th, 2015 AT 3:43 PM
Tiny
HMAC300
  • EXPERT
Because the pressure drops right away try the fuel pressure regulator it shold keep pressure for at least 5-10 minutes before dropping. The temp sensor is supposed to be wired like I said the blak/wht wire goes back to gauge. So look for another wire and recheck the part. After looking at sensor I think you have the wrong sensor. I'm sending a pic of correc part, wired connector and location.
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Saturday, April 18th, 2015 AT 4:03 PM
Tiny
BELLEAUT
  • MEMBER
Hmac300
Your information was spot on. The fuel regulator was bad. I replaced it and the truck is running much better now.

I still have the original problem of my temperature gauge not working. The pictures really help. (The best I have seen so far) I did find both, the coolant temperature sending unit and the ECT. I replaced the sending unit with no change on the gauge. I believe I already wrote this in a earlier post so I am sorry for repeating myself. I replaced this one based on a youtube video I saw. The video was based on a truck that was much older than mine. The truck in the video probably did not have an ECT or a computer for that matter. (No fuel injection.)

My confusion is based on the test from the video. I grounded the only wire that connects to the Coolant temperature sending unit, turned the key on and the temperature gauge inside the truck bottomed out on the hot side. In other words it moved. If nothing else is it safe to say that the gauge should work once I find the problem?

After I read your post and looked at the picture I pulled the ECT. I did an OMS test on it and I also check for resistance using hot water. The ECT tested positive. My guess now is a bad wire somewhere. I tried to do a voltage test on the ETC wires. With the key on I did get some voltage off of one wire. How do I test the other wire? (Sorry, I do not remember the colors because I did the test a few days ago) I would like to complete the test before I try to sort through all the wires.

I am trying to get this fixed because the computer is not reading the temp. I am still getting code 21 that states the temp sensor is out of range.

I do appreciate your feedback and your patience. I do most of my own work but I have never owned a ford ranger 2.9 before. I am trying to learn my way around this one.

Thank you again.
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Tuesday, April 21st, 2015 AT 6:58 PM
Tiny
HMAC300
  • EXPERT
The one wire that is getting voltage if grounded out will make the gauge go up to hot. If it'snot moving it may be the ground wire is the problem. I gave the color codes in one of the replies already so check the one going to the gauge. It can be a bad connection as well that is why I sent a pic of connector to temp sender. The code 21may be from the ect however so check connections at pcm and ect due to age of truck.
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Wednesday, April 22nd, 2015 AT 7:38 AM

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