Delta88Olds73

Hello to all and I need help. 73 Olds delta 88. I want to get it to safe to drive around town mode and Im not sure if im getting closer to that or not. Okay im gonna jump right in. I changed headlight switch because there were dead spots where dash would go out there was a sweet spot where the lights would work. Let me add that my car is beat up, not in great condition at all. Who ever had the car before the guy I bought it from wasnt kind to the car. Im not sure how long it sat parked in the woods but you could see neglect on top of neglect. Bee hive underneath car very dirty with some rust so im literally finding one bad thing after another so keep that in mind. Alright, back to problems. Two main issues. fuel gauge stuck on full. and passenger tail light goes dead when you press brake, with lights on. Lights off it works fine. Turn signal same way. also driver side middle bulb is brighter than outer only on driver side. What have I done so far?? Religiously cleaned ground connections and plug ins. All light bulb sockets wirebrushed cleaned. ground area cleaned to bare metal and regrounded. I bought new brakelight switch and bulbs. regrounded front headlight from harness right behind battery. took apart EACH connection and thoroughly cleaned. Now i do need help understanded the jump wire ohm resistor method for fuel gauge. Honestly I thought to fix brakelight issue first but Im open for suggestions. I also changed out door jam switch but my dome light has literally rusted out so I gotta get a new one. I just need the terminals I still have dome light. Would that effect brakelights?? Im gonna take some pics so you can see what im speaking about. Thank you in advance... HELP!!! oh I have multimeter, where can I find those resistor wires at?? Been looking online not sure which ones to get or where without having to have them shipped. I would prefer to just go pick them up.. thanks again.. any help is good help

jaunty75

I don't know what the "jump wire" method is, either, but a fuel gauge that pegs at full is the classic symptom of an open circuit. It could be where the ground wire coming off the sending unit at the tank attaches to the body of the car. This connection can become corroded or loose or even fall off altogether. You need to get under the car towards the front of tank to check. The other possibility is the sending unit itself, and that requires replacing it, which means removing the gas tank. Fortunately for you, new sending units are available for your car. Rockauto has them for about $50.

Good diagnostic practice, though, is to also verify that the dash gauge is working properly, and you do this by disconnecting the other (non-ground) wire coming from the sending unit from the wire coming from the front of the car. These are joined in the area behind the license plate, and there is a connector you can pull apart. Pull it apart, ground the side coming from the gauge, and turn the ignition key ON. The gauge needle should go immediately to E. Then remove the wire from ground and watch the needle. It should go immediately to F or likely well past it. If the gauge does these things, you have verified that the dash gauge and the wiring to it are ok and that the problem is in fact at the rear of the car.

JohnnyBs68S

Jaunty gave you solid advice on the fuel gauge, so I have nothing to add there. The "resistor wires" are only in your ignition system (assuming NO HEI), so its unlikely you have a problem there. Your tail light issue definitely sounds like a bad ground, but can't rule out the possibility of a supply-side problem either. Your dome light shouldn't have anything to do w/ your tail lights, but it does run off of the headlamp switch since rotating that to the brightest dash light setting should turn on the dome light (over-riding the door switches). Check all wires and connections, especially in the fuse panel (verify these are all OK and not corroded). Rust in the electrical system SUCKS and can make it tough to locate the root cause. Keep at it, you'll find it.

Delta88Olds73

Jaunty75 thanks for reaching out. I figured out tail light issue.. BAD GROUND wire that goes into socket itself. Both were rusted out bad, Didnt notice it first time around I thought I cleaned them good. So I got two new ones im going to pick up shortly. I tried to just clean them good but they are beat up pretty bad. I put hazards on and passenger tail light was actually flashing like I had signal on. I pulled them out the housing and jiggled the ground wires and they were dancing all over the place. Dimming out, flashing, they are cooked. So thats a good problem so to speak. Would you happen to have a link or picture of what it looks like to ground fuel guage wire? This is something I need to get better at. If you dont no worries I will figure it out im sure. Thanks again Jaunty75 I keep you posted

Delta88Olds73

JohnnyBs68S how are you Brotha? Thanks for reaching out. So I figured out tail light issue, bad ground wires going into the sockets themselves.. BOTH of them are fried! I got new ones im going to get in a few. Considering this car has been thru WWII and back im not surprised at what im finding as I try to get certain sockets back working. Literally NONE of the lamps worked except head and tail lights. all other light bulbs / sockets did not work. Corroded dirty rusty is an understatement!! I even got the dome light working again. Now about fuel gauge im going out to try to get it to move. Ive already cleaned the ground wire on front of fuel tank underneath car. I was hoping that was it cuz it was way past dirty. bare metal cleaned the connection really good and nothing.. So on to the next test. Thanks again for your help. I let you know how today goes.

jaunty75

I don't have any photos, but I do have some scenes from the 1973 Olds chassis service manual that are applicable to your car.


This one shows how the sending unit goes in.






This one will be helpful in finding the connection between the sending unit and the gauge wire from the front of the car. The connection is actually inside the trunk right next to the trunk lid latch. The wires pass through a grommet, and the connector you need to pull apart is circled in red in the upper right of the figure.

Delta88Olds73

Okay so here is the question now.. I grounded connection coming from fuel gauge and the fuel needle went to E. So.... this means that the fuel sending unit is bad right? When the fuel sending unit has failed it doesnt recognize the ground wire coming from unit anymore? This means my ground wire that I took off and cleaned and screwed back is indeed good? I understand that the gauge works because it moved, Im trying to understand what am I proving towards narrowing it down to either ground wire is still dirty and needs to be cleaned again or the fuel sending unit is bad? Did that make sense? Thanks

jaunty75

By separating that connector, grounding the side coming from the gauge, and observing that the needle moves to E when you turn the ignition ON proves that the wiring from the front of the car to the rear is in good working condition and that the gauge itself is working fine. So your problem is at the rear of the car. It is either the sending unit itself or the sending unit ground wire connection. If you have removed the ground wire, cleaned it and its connection point, reconnected everything, and the gauge STILL reads past F when you turn the ignition on, then the problem is the sending unit itself. You are now done making fuel gauge system tests because you now know what the problem is. You need to remove the gas tank from the car, remove the old sending unit,and install a new one.

Delta88Olds73

couldnt have said it better. I cleaned the ground wire like a maniac.. Its not the ground. I also looked on Rock Auto.com. They don't have the FG110B in stock but I appreciate the look out. Thank you for taking time out to answer my questions and concerns. PEACE OUT!!!!

jaunty75

If Rockauto has it, it's likely your local auto parts store can also get it. Check with O'Reilly or Autozone or NAPA or whatever. You'll likely have to order it and have it delivered either to you or the store, but someone is likely to have it.

jaunty75

Amazon has it in stock. It turns out that this is the same sending unit that my car ('78 Toronado) uses. I bought one of these in 2017.

Vintage Chief

JohnnyBs68S

Glad to hear you are figuring out your electrical issues. What's next?

Oldssupreme

This thread is very helpful. Glad it’s revived and I found it

Delta88Olds73

see what I mean. no blower access like book illustrates or am I looking at it the wrong way?

my set up doesnt look like book at all. It says there should be a ground wire coming from blower??

This is the high blower relay I replaced because one of these metal prongs had literally rusted off into the connector. but this doesnt need a ground wire from body of car right?

mystery ground wire. Not sure where it should go.

coming out tail pipe. timing off? book says 12 degrees btdc. Should I advance timing? Definitely not running good tho. sluggish

The high blower relay doesnt need a ground wire does it?? I really think the previous owners did alot of things to this car with no reference at all. Alterations have been made to things that I cant figure out why? Is this how the car left the manufacturing plant or have things been taken off without a replacement? Im not sure if I should be able to see the blower or not. It doesnt seem like there would be a reason to ground the relay to the body. Help me out guys!! Thanks in advance