Early V6 oil pressure sender to 1988 style conversion (Page 3/4)
theogre JUN 13, 11:54 PM
Dash lights out...
See my Cave, Dash Dimmer

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)


The Ogre's Fiero Cave

Skybax JUN 14, 02:08 PM

quote
Originally posted by Blacktree:

OK, now we're getting somewhere. Sounds like the dimmer transistor is bad.

The dimmer switch doesn't directly control the lights. It sends a signal to a transistor. The transistor uses that signal to determine how much power to send to the dash lights. That green wire you mentioned (should be dark green with white stripe) goes to the dimmer transistor. Also, the transistor powers the INST fuse.

So if you have power going through the dimmer switch, but the INST fuse has no power, then something's up with the transistor. That transistor is mounted under the dash, beside the steering column. It has an aluminum heatsink. See photo in link below.

http://rodneydickman.com/pr....php?products_id=513

There should be 3 wires attached to the transistor. The brown wire is power from the headlight switch. The dark green with white stripe is signal from the dimmer switch. The dark green wire is power to the dash lights. You can test the circuit by jumping the brown wire to the green wire. That will bypass the transistor and send power to the dash lights (if the parking lights are on). If the dash lights come on when you bypass the transistor, then the transistor is dead. You can buy the one in the link above for a reasonable price.

Best of luck!



Update... 5 minutes after you posted your message yesterday a storm cell came thru with micro-burst and knocked out power for the last 20+ hours, so the power just came back on about 30 minutes ago. Yes you are correct, when I disconnected the connector for the transistor and jumped dark brown to green the dash lights lit up, so I'm going to buy one from Rodney. Thank you for assisting me in helping to figure out a frustrating problem within 24 hours, because it might have taken me all week to figure out without your help, and just in time before the storm hit, thanks again!

[This message has been edited by Skybax (edited 06-14-2021).]

Skybax JUN 14, 02:17 PM

quote
Originally posted by fierofool:

I installed my new ACDelco sending unit. Doesn't blow the fuse any more. Gauge still stays pegged to the far right bottom as if it doesn't have a ground.

Does anyone have a known good used sending unit they're willing to sell?




I purchased an NOS 85-87 oil pressure sender and going to make my own connector because I'm going back to the original style. So if you want to buy my new 1988 AC Delco oil sender that was installed on my car for only a few days you can have it (and the new connector) for half price shipped.

(gauge worked perfectly and had no issues, aside from the coincidental dash light dimmer transistor failure).

I'm currently swamped with tasks due to no power last 24 hours so just send me PM if you want it...

[This message has been edited by Skybax (edited 06-14-2021).]

Blacktree JUN 14, 03:05 PM

quote
Originally posted by Skybax: Thank you for assisting me in helping to figure out a frustrating problem within 24 hours, because it might have taken me all week to figure out without your help, and just in time before the storm hit, thanks again!


Awesome!
Skybax JUN 14, 03:31 PM

quote
Originally posted by theogre:

Dash lights out...
See my Cave, Dash Dimmer




Great info and will be useful during replacement, thanks.

fierofool JUN 14, 05:36 PM
Skybax, PM sent.
fierofool JUN 21, 09:38 PM
Well, I picked up Skybax's known good 88 sending unit and installed it today. As described above, the ACDelco unit I was running was keeping the gauge pegged and I discovered that the fuel pump was also continuing to run. The first 88 sender was a Standard Ignition part and it would blow the fuse for the instrument panel as soon as I turned on the ignition.

Surprise! The ACDelco unit from Skybax blows the fuse, also. So, I have a Standard Ignition and an ACDelco sender that both blow the fuse and another ACDelco sender that keeps the gauge pegged and the fuel pump energized. It has me puzzled as to whether it's sending units or wiring. If it's wiring, I shouldn't get 2 different problems, especially with the same brand units. I put my old ACDelco back in after replacing the fuse, and it pegs the gauge with with ignition on and keeps the fuel pump energized with ignition off. So, it's currently unplugged, just leaving the gauge pegged.

Time to re-recheck the harness conversion and maybe replace the gauge unit. I would also welcome any ideas. Anyone know how to test the sending unit with it out of the car?

BTW, to skybax. When he learned that the unit didn't solve my problem, he refunded half the already discounted price I paid him for his new ACDelco sender.

[This message has been edited by fierofool (edited 06-21-2021).]

Skybax JUN 21, 09:53 PM
My instinct tells me it has nothing to do with oil gauge aspect, because that doesn't come into play yet when you turn the ignition on, so the fuel pump circuit does go live when you turn the key on via the ecm which energizes fuel pump for a few seconds, and the #2 oil sender / fuel pump fuse is hot through the fuse box at all times.

With the oil sender disconnected, does it still prime the pump the same and start up relativity quickly?

Does the car stay running if you unplug the oil sender while running?

I will meditate on this some more...

[This message has been edited by Skybax (edited 06-21-2021).]

fierofool JUN 22, 02:05 PM
It has always taken 2 or 3 attempts to start when it's cold. It starts quickly when warmed. New fp relay. The pump primes with or without the sender plugged up. Gauge stays pegged with or without the sender plugged up, except for the ones that blow fuses. I've been running it for months with the sender unplugged. I'm still running the original fuel pump.
Skybax JUN 22, 11:55 PM

quote
Originally posted by fierofool:

It has always taken 2 or 3 attempts to start when it's cold. It starts quickly when warmed.



Cold start injector not working? (unrelated to current blowing fuse issue)

Hopefully one of the electrical guru's on here can offer some insight...