'88 --3.8 TBird Cooling August 27, 2012, 05:33:09 PM On and off for some time I have been trying to get to the bottom of the high range coolant temp needle on the dash. I have addressed much of everything on this problem. For years before 2007, this Tbird gauge would only measure in the low end of the scale in all conditions--now it's been the opposite. Today I just replaced the thermostat (now 195 F ; was 193 F) and replaced the temp sensor directly above the thermostat--fitted with a push on wire. Seems there are two on this engine? The other is closer to the distributor cap and has a pinched type plastic type connector mounted on it- two wire. I have now replaced both. The engine cold starts and before the radiator can even get hot, the needle already is where the pic shows. It pretty much stays there and even creeps up at times -being near the red hash mark if I am stopped. The antifreeze isnt new but I have driven with aged antifreeze in many cars without any problems over the years. ?? I see no sign of head gasket problems either. Quote Selected
'88 --3.8 TBird Cooling Reply #1 – August 27, 2012, 06:43:47 PM You need to warm up the engine and measure the resistance of the 1 wire sender to ground, then measure voltage there on the red/white with it disconnected. You're looking for 5 volts. Reconnect with the engine still hot, pull the cluster and measure resistance to ground on R/W again, compare to the resistance reading you took directly off the sender (you may want to re-measure at the sender at that time just to be safe). The allowable variation is low, the sender measurement should be within .2-.5 ohms. If it specs out the same as the sender you need a cluster, if not, you need to measure resistance of the circuit (with the key off and out) which SHOULD be .2 to .5 end to end, but if we're at this step, you'll likely find much more. Dive in after the source of the high resistance, repair as necessary.The wiring diagram, for your reference. Quote Selected
'88 --3.8 TBird Cooling Reply #2 – August 28, 2012, 09:56:46 PM Thefoeyouknow---- Thanks for the technical reply as you put some effort into it and I appreciate the diagram. All other components on this vehicle appear normal----I will have to digest this info and decide whether I can play electrical tech to the level you have subscribed me to!!! I do have a vom. Fortunately, I have taken the cluster out before, twice--to replace a bulb. That was 10+ years ago. Amazing how that is---once you get past a bunch of burned out bulbs at about 10-15 years old, the rest hang in there forever! Quote Selected
'88 --3.8 TBird Cooling Reply #3 – August 29, 2012, 01:03:44 AM i would venture to say you should be paying attention to the wire called the "un insulated" wire ~the resistance wire.its a small gray wire on your ign switch , if you skin it back its a single solid conductor but no need to skin it.with the cluster out, measure the resistance from the instrument cluster connector to the ign switch. maybe for you it would be easier to swap in a different cluster to verify if its "car" or "cluster". These clusters are easy to get your hands on.the IVR is making the voltage out to the guage, if the resistance wire is over heated at the ign switch , i will effect your fuel and temp guage.having trouble being 100% sure your fuel guage is actually correct? do you seem to hit totally empty when the needle hits "E"?does your fuel guage seem to read way higher than "F" and hold there for an unusual period of time say 150miles then quickly drops to 1/2 in like 40 to 50 miles? Quote Selected
'88 --3.8 TBird Cooling Reply #4 – August 30, 2012, 12:14:04 AM jcassity: "having trouble being 100% sure your fuel guage is actually correct? do you seem to hit totally empty when the needle hits "E"? does your fuel guage seem to read way higher than "F" and hold there for an unusual period of time say 150miles then quickly drops to 1/2 in like 40 to 50 miles? "Interesting question----this was the Mrs car from Jan 1988 to April 2008. She has always commented that the gas needle had a characteristic quick drop once it started to move off full--particularily when less than 1/2. When the tank is filled completely, the needle is moved some distance beyond the Full mark and freezes there until maybe 4 gallons are gone(and this is a guess). The gas gauge on this TBird is like the old VW Beetle--which had a similar action (for those of those who drove air cooled beetles pre 1972). Not sure on the empty--we tried always to avoid that scenario, but it seemed to have the magical "Reserve" like the old VW. The VW, tho, had a specific marking on the gas gauge showing that. Empty happened once in our driveway (luckily) and I cant remember the needle. I probably could fill the tank and shoot a pic of the needle. Overall, the gas gauge presentation has not changed in 24 years on the TBird. The big question for all --is this the designed activity for the car and not a fault?Another thought based on your comment was the ignition switch. This car had a recall and the switch was replaced in 1994 (Long ago...). In 2005, I removed the lock cylinder to file a burr on it. The burr was causing the keyswitch to seize in some positions--very annoying. I ended up doing that on the 2 Fords we have and the problem was solved. I dont remember the work but I dont believe the repair relates to any electrical problem I could have caused there--as I dont believe any wiring except the key gong warning (door open) was involved? BUT? Quote Selected
'88 --3.8 TBird Cooling Reply #5 – August 30, 2012, 10:50:39 AM Quote from: JKATHRE;396973 Overall, the gas gauge presentation has not changed in 24 years on the TBird. The big question for all --is this the designed activity for the car and not a fault? Absolutely yes. That's how they are. I fiddled around with mine for a couple of months on and off. My car would not move off of the red E hatch until 6-8 gallons were in the car. It was a 21 gallon tank and it would still go above full when I stopped at the pump. I tried 2 sending units, and a different gas tank. Same problem. Next time you fill it up, run it down to the red "E" area. Make note of how many gallons you've added. If it's 15-16, you'll know when on E, you still have quite a ways you can go. Not that I recommend it though. Quote Selected
'88 --3.8 TBird Cooling Reply #6 – August 30, 2012, 10:18:30 PM Today I topped the tank--although I recall similar results over the years--when you pay attention it does seem odd. If you see the gauge in the above pic, now it looks like the pic here, but it took 10 gallons to go that short distance!! The book says the tank is 22.1 gallons. I recall testing the matter and having the needle on E and we filled it 20 gallons. So the car has a 2 gallon cushion--(now that I thought about it and see jpc647's comments above, I do recall learning this some time ago). I drove the car today in 90 F heat at 6 pm--varying speeds up to 45mph and had no problem other than the gauge is the way it is now. I will consider getting a cluster if it is inexpensive--you just dont see many 80's T-birds around here anymore. I'll have to check the bone yards. Quote Selected
'88 --3.8 TBird Cooling Reply #7 – August 31, 2012, 05:20:40 AM You have a bad 5V regulator. They go bad all the time. Easiest way to determine this is BOTH GAUGES READ HIGH. To further check but i dont know why you would it is totally clear the gauges are over voltage. You can put a standard test light from ground to the removed temp lead and key the ignition. If the light pulses the regulator is OK if not it will stay steady. Those regulators go bad all the TIME. I loved the answer FOE gave FASCINATING AT BEST!! http://www.ebay.com/ctg/Standard-Motor-Products-VRC606-Instrument-Cluster-Voltage-Regulator-Switch-/76715898NOTE you can carefully remove the cover and burnish the contacts on your unit. Then replace the cover. Normally the contacts fuse together. I have fixed many of these in my career. Or they sell electronic ones that work much better. One other thing. If you key the car and the gauge goes up smoothly the regulator is shot. If the gauge goes up with a slight pulsing motion the regulator is OK. This is a simple test that i do to see if the regulator is BAD!!! This can be dun right in the drivers seat. Key the car and watch the fuel gauge for slight needle pulses. If it pulses the regulator is OK. But yours is most likely bad. (contacts fused)Here is one on a TC dash check it out!! Quote Selected
'88 --3.8 TBird Cooling Reply #8 – August 31, 2012, 07:10:47 AM There is nothing wrong with my answer. It tests the circuit and the components. The Ivr is not tested, because the gauge is not pegged. Clearly i instructed him to test for proper vref at the component. He would have come down to a bad sender, high resistance, or a bad cluster, if he came down to a bad cluster and wanted to shag around testing the ivr, that would have been up to him at that time, but he'd have followed a diagnostic procedure to that point, and he'd know he was in the right place instead of just taking somebody's word for it and throwing the parts at it he was told to. Quote Selected
'88 --3.8 TBird Cooling Reply #9 – August 31, 2012, 08:25:56 AM Quote from: JKATHRE;397016Today I topped the tank--although I recall similar results over the years--when you pay attention it does seem odd. If you see the gauge in the above pic, now it looks like the pic here, but it took 10 gallons to go that short distance!! The book says the tank is 22.1 gallons. I recall testing the matter and having the needle on E and we filled it 20 gallons. So the car has a 2 gallon cushion--(now that I thought about it and see jpc647's comments above, I do recall learning this some time ago). I drove the car today in 90 F heat at 6 pm--varying speeds up to 45mph and had no problem other than the gauge is the way it is now. I will consider getting a cluster if it is inexpensive--you just dont see many 80's T-birds around here anymore. I'll have to check the bone yards. I tried swapping clusters before to no avail to this "problem". Now my car probably would have only maybe taken 5 gallons to go that distance, so our problems are related, but may be slightly different. Mine took a long time to come up off of E, yours takes a long time to get full past F. So our problems could actually be opposite. Although I don't have my car anymore, so I can't check. Quote Selected
'88 --3.8 TBird Cooling Reply #10 – August 31, 2012, 11:53:26 AM FOE simmer down!! I just for the life of me cant figure what the hell you were talking about with that trouble shooting procedure ???? Quote Selected
'88 --3.8 TBird Cooling Reply #11 – August 31, 2012, 02:50:18 PM It was a way of checking that the signal arrives as it was sent. It would be helpful, I suppose to have the reference values for the component, but my method would have ruled out the circuit, and a new sender is cheap enough to sacrifice to the "known good part" method. A known good part and a verified circuit, means a problem in the cluster. With a determined cluster problem, I would have taken him into diag of the cluster, probably pointing to the ivr. If it doesn't seem make sense, it's because it's incomplete. He stated that he didn't know if he wanted to go that deep into diag, so I didn't supply any further directions. Quote Selected
'88 --3.8 TBird Cooling Reply #12 – August 31, 2012, 10:19:12 PM It was a way of checking that the signal arrives as it was sent.Still BAFFLED??? Quote Selected
'88 --3.8 TBird Cooling Reply #13 – August 31, 2012, 10:35:28 PM Hi guys--- The dash voltage regulator looks like the way to go because it is cheaper and avoids playing roulette with a used cluster. I even thought of just installing a temperature gauge to get around this issue. Please tell me, is this regulator inside the cluster container (that's what the picture suggests)--how do I locate it? It also seems logical to see if I could repair it first. JR Quote Selected
'88 --3.8 TBird Cooling Reply #14 – August 31, 2012, 11:04:58 PM Pull the dash and you will see it. once you remove it a new one is like 20 BUCKS!!! But i do not like the electro mechanical units so i use electronic ones. But you can use a small pair of pliers and a small screwdriver to remove the cover of your regulator and burnish the contacts. This normally repairs them nicely. Then reinstall the cover. Just make sure you pinch the wire that is between the crimp. That is the ground for the regulator. Go slow and be careful and you can repair your VIR. Dont install an aftermarket gauge. They in my view are silly. Unless you do an entire custom dash. Good luck TomAlso it is a must to repair your dash as the fuel gauge is also involved!!!! Quote Selected
Topic: '88 --3.8 TBird Cooling (Read 7597 times)
previous topic - next topic
