Okay so I just finished the temp gauge repair as per the write up shown here http://www.fierosails.com/tempgage.html It went well and only took about an hour just wanted to say thank you to the folks who provided the writeup.
------------------ Honestly, What is a "stock" Fiero?
Did you have to splice-in longer wires to switch the connectors from one dash harness connector to the other? Did you have any problems removing the temperature wiring connector from the engine? My connector cracked when I removed it to switch the wires over. Rodney Dickman sells the replacement engine wiring connectors for $4.
------------------ Now new owner of a Black TTop 88 Fiero GT and owner of a Silver 88 Fiero GT. Also a second time owner of an 85 Fiero GT. Bought my first fully loaded Red Fiero GT new in 1985. Fiero's are Fabulous, Fix'em and have Fun! Note, Avatar picture is Mr. Bean (not me, ha ha).
Since this isn't too horribly old, resurrecting to repeat the previous question. I've swapped the wires at the sender with no issue (took me a minute to realize you had to open that flap on the side of the connector, this isn't really my forte), and been able to push the two wires out of the plugs at the gauges. However, there's nowhere near enough slack in the individual wires, and my best guess is there wouldn't be enough slack gained by cutting the tape around the wires open from the plugs back to where the harnesses go up into the dash. Can anyone confirm this should be sufficient slack? I wouldn't even know where to begin with trying to add new lengths of wire...
(ETA: image showing how annoyingly close I am to hopefully having this fixed)
[This message has been edited by commodore_dude (edited 05-23-2013).]
I bit the bullet and cut the tape off both bundles of wires, swapped the two green wires and re-taped the bundles. There wasn't enough slack to incorporate the swapped wires into the respective bundles, but I was able to get everything plugged back in - there seems to be more slack on wire being swapped over to the passenger side than on the wire being swapped to the driver side. Unfortunately, while the temp warning light does now come on briefly when the engine is cranked (I was expecting it to happen with the key just to Run but I guess the other lights don't test then either), the new temp gauge never goes above 100. It does rise from the rest position below 100 so it's getting power, but obviously something is still not right (all other gauges are functioning as before, including the new fuel gauge - I moved the needle on the new one to a position that was fairly different than on the old gauge to make sure it would adjust). Ugh.
Update: After backing away for a bit to avoid being too mad at it, I *think* I properly grounded each pin from the temp sensor plug to the engine with the ignition on Run. No temp warning light, no change in temp gauge. I am getting 12v from both pins if I'm operating my $3 Harbor Freight multimeter properly, and that also serves to ground the pins properly (seriously, not an electrician here). Now, if we look at the wiring diagram, I'm assuming somewhere at the C2/D3/C500 point, something else in the wiring is supplying voltage back down to the sensor plug? What besides wire 11 could be providing voltage to the temp gauge to make it raise up to 100 degrees when the ignition is on?
[This message has been edited by commodore_dude (edited 05-28-2013).]
don't forget to switch the wires at you actual sensor on the block, if you do not do this the temp gauge will only read 100. I did this fix over the weekend and mine was showing 100 also, switched the wires at the sensor and all was well. Reading this thread last week finally gave me the push i needed to fix it.
don't forget to switch the wires at you actual sensor on the block, if you do not do this the temp gauge will only read 100. I did this fix over the weekend and mine was showing 100 also, switched the wires at the sensor and all was well. Reading this thread last week finally gave me the push i needed to fix it.
Switching the wires at the sensor is the first thing I did - wish the rest was that easy! Even if I hadn't, I would still expect that what I did to try and ground out those wires should have pegged the gauge and tripped the warning light, respectively, since at that point they wouldn't be going off of being plugged into the sender put rather just off of getting grounded to the chassis. Is this correct?
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Originally posted by Gall757:
As the gauges are inexpensive and inaccurate, the 100 you are seeing is probably ambient temperature.
I'm not sure I understand this bit. I'm using a brand new gauge, and it sure wasn't inexpensive at least by my standards . Do you mean the sender? If the sender was bad, which I'd kind of expect given that I had to replace a bad oil pressure sender and that fixed my oil pressure gauge/warning light, I would expect that grounding the wires in the plug going to the sender would have produced some reaction at the dash. So I still think either there's a break in the wiring somewhere between the plug and the dash, perhaps a break somewhere on the dash itself, or I'm just not doing something with my multimeter that is actually grounding out the wires at the plug. Therefore, I'm seeking ideas for what I might try to figure out where the disconnect is.
[This message has been edited by commodore_dude (edited 06-04-2013).]
The gauge should move to the 100 degree mark with ignition ON, no start, unless the temp is above that. It doesn't necessarily indicate ambient temperature. It's one way of verifying gauge accuracy and that the needle hasn't slipped due to needing the above noted fix.
Any idea what provides power for the gauge to move to 100? Is it a different wire than the one coming from the temp sender at the engine? If so, that still lends credence to my idea that there's something wrong in between the gauge and the sender. If not, I got nothin.
I don't know unless there's a resistor in the circuit. If the needle slips due to the bump at startup it could read incorrectly.
've owned 6 or 7 Fieros and every one that was close to being accurate moved to about the 100 degree mark when the ignition was turned on. When I say close to accurate, I mean that they were indicating close to the correct temperature when the cooling fan kicked on and they indicated just below 200 degrees at operating temperature.
I currently have one car that the needle sits back closer to the bulb on the thermometer symbol and it only shows a little above quarter-gauge at operating temp.
This was the second time I have done this procedure. The first time I cut and spliced. This time I removed the bundle tape on both sides and there was enough wire length to make the swap. It was a little tight as someone posted above but plenty to do the job. Mine is working correctly.
I can't conceive of any scenario where the problem is the gauge. It's a brand new gauge. Therefore, I'm trying to figure out what else could be the problem here given all of the other behaviors I posted (I thought I'd mentioned before, but it looks like I hadn't, that the previous gauge would also just sit at 100 when the needle deigned to not be stuck up at the top of the gauge). If I knew some way to try to get the gauge to react other than grounding out the wires at the sender, since either something is broken there or I'm doing it wrong, or if I knew some way to verify that the sender is good without having it plugged in, or some way to check that wire at the dash coming from the temp sender, one of those is probably what I need to know to try next.
[This message has been edited by commodore_dude (edited 06-06-2013).]
Put the negative probe on the hex base of the sensor and the positive probe on each of the terminals. One will give you no reading since it's the one for the light and that doesn't complete a circuit until overheating occurs. The other will be the variable and it registers temperature at all times so it will give you a reading of what it thinks it's surrounding temp is. Compare that reading to the chart to see if it's anywhere close to your ambient temp.
So, if the temperature of the sensor is about 70 degrees, you should get a reading of somewhere around 3400 Ohms. If you want to bring it up to operating temp, you should get a reading of about 260 Ohms at 190 degrees. A more accurate method of checking is with a digital infrared thermometer. Put the laser beam on the base of the sensor and you can compare real-time operating temps to your temp gauge. Harbour Freight has them at a relatively low price. I caught mine on sale for $30. Good for checking brake temps and for coolant flow throughout your cooling system or you can even find a defective injector, plug or plug wire by aiming it at your exhaust ports on the manifolds. An added bonus is that the dogs and cats just love to chase the red dot.
I actually bought one of those before I flew out to Texas to drive it home last summer since I knew the temp gauge didn't work (every time I checked the rad hoses they were between 200 and 210 even on a 105 degree day), so hopefully I'm all set to try this tonight!
Originally posted by fierofool:So, if the temperature of the sensor is about 70 degrees, you should get a reading of somewhere around 3400 Ohms. If you want to bring it up to operating temp, you should get a reading of about 260 Ohms at 190 degrees.
Thanks for this. My temp gauge shows ~100 with the key on and the engine cold, and climbs to 180 or 190 very shortly after getting on the road. In traffic, the gauge continues to rise quickly but the fans never turn on. I've replaced all the sensors & switches, verified the fans and the fan relays work (by powering the fans, grounding the fan switch wiring at the engine, and turning on the AC), but no amount of indicated engine temperature causes the fans to cycle. The entire cooling system (radiator, tubes, hoses, water pump - even head gaskets) is new as of ~20,000 miles ago, and there seems to be good coolant flow and no loss. I gotta believe my gauge is just reading inaccurately - now I can test the sensor to see if it and the gauge disagree.
Well, I've been trying to get my multimeter to show anything for days, but it'll only give a reading of "1" on the temp sender no matter what I do. Seems to work on other stuff, or at least sometimes show things other than 1...
Damn, has it really been 2 months? Anyway, I never could get grounding out the pins in the plug to work, I never could figure out how to read the resistance of the sender, but I happened to catch a new AC Delco sender on closeout at Rockauto for 10 bucks and I couldn't resist. Gauge goes to 220, fan comes on, gauge drops a bit, fan goes off. I'm a happy camper. Protip for anyone else like me that had never changed a temp sender before - there's coolant behind it, and it goes everywhere FAST. Oops.
Bringing back an old tread, I did this fix and even before the gauge doesn't seem to work. I filled my system and my light is on, and in about 4-6 mins. the gauge pegs itself. I have no idea if the motor is over heating or if I have a bad gauge? I also replaced both sensors to see if that fixes the issues and the problems are still the same. The whole time I've owned Fieros I've never had very good luck with the coolant system or the gauge. I don't know what my problem is either.
[This message has been edited by Fierokid87 (edited 08-12-2016).]
If you are getting both a light and a high reading on the gauge, my guess is you are overheating. It's unlikely both are failing giving false positives.
This is weird because you have both problems. The wiring is separate so it doesn't make any sense that both are flaking out.
Key on, engine off what happens when you individually ground each of the wires that run to the sending unit at the engine? Does the light light? Does the gauge move?
This is weird because you have both problems. The wiring is separate so it doesn't make any sense that both are flaking out.
Key on, engine off what happens when you individually ground each of the wires that run to the sending unit at the engine? Does the light light? Does the gauge move?
I tried Unplugging the light sensor and the light stayed on. So maybe something is grounding out? Not sure where though. Not sure how I should test the gauge sender.
Did you mean you unplugged the coolant temperature sensor? Also make sure that you unplug the correct temperature sensor. 4 and 6 have different locations, of course, but ECM gets a temperature sensor, and the two instrument functions on the dash get a separate temperature sensor. And neither should be confused with the MAT.
The light sensor is on the intake manifold just below the Tstat and above the water pump, and the gauge sender is on the head. Neither of which seem to be functioning properly. I'm getting so flustered with this car. I'm afraid to drive it anywhere so she spends most of her time in the garage. When the light fist came on it was two weeks ago when the timing chain cover gasket let go and I was spewing coolant everywhere. Since then the gasket was fixed and the water pump was replaced. And the light refuses to turn off. So I replace that sensor and the light is still on. I also tried changing to temp gauge sender and the gauge still pegs in 30 seconds. I'm at a total loss here. Short of doing an engine swap which would probablyou solve all of my issues I don't know what to do. I'm seriously ready to give up on Fieros here. It's the same old song and dance with me and fieros. Overheating or acting like it's over heating for me seems to be the norm.
No! Don't give up. It is all solvable! And not with a complete engine swap. So if you don't already have them, just go to Harbor Freight and get a cheap voltmeter and an IR temperature sensor. The IR temperature sensor can verify that the coolant temperatures really are what the gauge claims that they are. And with the meter, you should be able to get us some voltages. When you disconnect the temp sensor connector, key on ignition, you should measure from each wire to ground. Both should be high, like 12v. Rodney has a cheap doodad that you plug into the connector to test all the way to the dash temp gauge.. http://rodneydickman.com/ca...h=22&products_id=282 If you turn on AC, does the fan come on?
This is after about 30 mins of driving the light has not turned off, however I pulled the Tstat out completely, and turned on the fan via the A/c button. It wouldn't budge past 3 -4 marks past 100. Put the Tstat in and the needle rockets to pegged......
Yes, dummy light does not turn off sounds like the wire is grounded somehwere along the line. If it were open, the light would never light. But the temp is interesting. If the tstat causes the temp to rocket, is it possible that you have very weak cooland circuilation.. so that it cannot push past the tstat. That would imply the pump, or possibly an obstruction. That doodad from Rodney would tell you if the gauge is fairly accurate or out in left field.
Oil got into my coolant. As it turns out the timing chain cover gasket eventually failed. Maybe the radiator is toast now? Maybe the oil got gunned up in the radiator and is now blocking up the radiator?
I pulled my cluster out and found the mylar board was so jacked up in the corners the copper wiring got all bunched together and was touching.
After I repaired the mylar circuit board on the back of my cluster, and replaced the temp and gas gauge with a brand new gauge unit, I no longer have the temp light staying on. However what I do still have is the gauge still pegging after running for about 4 mins. I did the fix a while ago where you swap the wires on the back of the cluster, and the two wires on the temp sensor but that was to keep the needle from pegging and getting stuck on start up. The new gauge doesn't spring or flop around like the old one did. It's nice and tight and new feeling. So I'm wondering if maybe I should put the wires back to what they were before?
. Do you mean the sender? If the sender was bad, which I'd kind of expect given that I had to replace a bad oil pressure sender and that fixed my oil pressure gauge/warning light, I would expect that grounding the wires in the plug going to the sender would have produced some reaction at the dash. So I still think either there's a break in the wiring somewhere between the plug and the dash, perhaps a break somewhere on the dash itself, or I'm just not doing something with my multimeter that is actually grounding out the wires at the plug. Therefore, I'm seeking ideas for what I might try to figure out where the disconnect is.
