Electrical Oil Pressure Gauge IN Dash Cluster Unresponsive

[Nine Finger Wrenching]

My oil pressure guage seems to be stuck in this position.

I thought at fist maybe it was just a bad sending unit, so when we rebuilt the motor I bought and installed a new one.

I read on here that you should take the wire off sending unit, ground it, needle sould bottom out was my understanding. It didn't move at all.

I thought maybe the whole sub cluster was bad. I didn't think fuel guage was working, but I put in 5 gallons of gas and think it maybe pretty accurate.

I clipped on test light to sending unit wire and touched ground and it lit up.

I had read where theres different pinouts for different clusters. I compared the pinouts and thought maybe. I looked at several things that were different like for instance Right Turn SIgnal. I checked and my right turn signal works, so that leads me to believe I'm pinned out correctly.

My uneducated guess is telling me to get new gauge for cluster, but I really don't know for sure.

Anyone have any suggestions on other testing procedures?

Thanks in advance!! Josh

 

[AeroCoupe]

What year car? What motor? What transmission? Was it originally a 4 cylinder and swapped to a V8? If it was swapped what year harnesses were used? Believe it or not we need more details than "my gauge doesn't work and here is what I have done to try to fix it" to help. Do not take this as me getting after you in a crappy way more driving the point home that the more details you can give about the car then the more info we have to try and help.

 

[AeroCoupe]

Quick search and jrichker to the rescue, Post #7 here:

C

Thread 'Help With Oil Pressure Gauge'

Mar 2, 2017

I'm sure this has been posted before. I just bought a 1991 gt 5.0. 106000 original miles . 1 owner. Everything is completely stock. I notice my oil pressure gauge needle stays at the bottom and when in issue it will drop below red. If i give it gas it will slowly go up but only 1/4 of the way. Where should I start to fix this problem . Should I be worried.

• Chad91gt
• Replies: 7
• Forum: Fox 5.0 Mustang Tech

 

[Nine Finger Wrenching]

What year car? What motor? What transmission? Was it originally a 4 cylinder and swapped to a V8? If it was swapped what year harnesses were used? Believe it or not we need more details than "my gauge doesn't work and here is what I have done to try to fix it" to help. Do not take this as me getting after you in a crappy way more driving the point home that the more details you can give about the car then the more info we have to try and help.

It all started in a small garage in Memphis, Tn. An ambitious man with 3 lads and little to no mechanical ability decided to buy a project car. LOL
I'm not scared nor offended by more questions. I don't feel you are trying to "get me in a crappy way" . If you are driving "A Point Home" then it is lost on me. If I knew what all details you wanted I could probally answer my own question.

The body is a 1991 GT.
The motor is a 302 out of an 89 GT vert.
The entire car has been converted to 89 harnesses.
It has a Borg Warner T5 transmission.

 

[Nine Finger Wrenching]

Quick search and jrichker to the rescue, Post #7 here:

C

Thread 'Help With Oil Pressure Gauge'

Mar 2, 2017

I'm sure this has been posted before. I just bought a 1991 gt 5.0. 106000 original miles . 1 owner. Everything is completely stock. I notice my oil pressure gauge needle stays at the bottom and when in issue it will drop below red. If i give it gas it will slowly go up but only 1/4 of the way. Where should I start to fix this problem . Should I be worried.

• Chad91gt
• Replies: 7
• Forum: Fox 5.0 Mustang Tech

I love jrichker!! He was the man. So cool he lives on here through all his content.

Believe it or not, I did this same quick search before I posted. I read all the Oil Guage threads. Didn't see what I thought answered my question or lead me to the next test procedure. so I guess there is no test for the guage itself, just process of elimination of everything else. So the answer to my question Is "No" there are no other suggestions or testing procedures.

 

[Mcmahst]

I think you did the only test I’ve ever heard for a Ford gauge which is to ground the wire that attaches to the measured sending unit. If the gauge doesn’t go to the max range, it’s likely the actual gauge that needs to be replaced. But, with the reality the car is not stock, and as you say, it’s been converted to an older wiring harness, it might be that.

If it were mine, I’d buy the replacement gauge.

 

[2000xp8]

If it were me, i'd buy an aftermarket full sweep oil pressure gauge. Even when the stock gauge is working, i'm not so sure it represents much.

 

[AeroCoupe]

You say the entire care has been swapped over to an 89 harness? Does this mean ECU, dash and body? I know with regards to the ECU harness the 89 will only work in an 89-87 car as the dash wiring harness connectors and wiring at those connectors is different on 90 and up with 90 being a one year only, 91-92.5 being by themselves and 92.5 through 93 being different again. Not saying you could not make a 91 dash harness work with an 89 harness if you have the wiring diagrams and take the time but its not plug an play. If the dash harness was swapped then you could get into some issues with the cluster as the 91 cluster is shaped a little different for the 91 air bag column unless that too was swapped to the 89 non-air bag column with tilt.

Try the gauge and if that doesn't work you may be chasing wires.

 

[Nine Finger Wrenching]

If it were me, i'd buy an aftermarket full sweep oil pressure gauge. Even when the stock gauge is working, i'm not so sure it represents much.

I understand, it is more of a Yes I have some amount of oil pressure, or no I have no oil pressure. LOL I'd like to make the dash work so I'll probally be ordering a replacement. But I do think I'd like a set of real gauges as well.

 

[Nine Finger Wrenching]

You say the entire care has been swapped over to an 89 harness? Does this mean ECU, dash and body? I know with regards to the ECU harness the 89 will only work in an 89-87 car as the dash wiring harness connectors and wiring at those connectors is different on 90 and up with 90 being a one year only, 91-92.5 being by themselves and 92.5 through 93 being different again. Not saying you could not make a 91 dash harness work with an 89 harness if you have the wiring diagrams and take the time but its not plug an play. If the dash harness was swapped then you could get into some issues with the cluster as the 91 cluster is shaped a little different for the 91 air bag column unless that too was swapped to the 89 non-air bag column with tilt.

Try the gauge and if that doesn't work you may be chasing wires.

Yes the entire car was redone with 89 harnesses. I do have the 89' column with tilt. I got a 89' dash and cluster to match. The motor, engine harness and ECU were all 89' It had an American Auto wire classic harness partially installed, but I removed that. I wanted factory so I went and got 89 taillight harness, dash harness, and headlight harness,....you know ALL the harnesses!... LOL I went through them all, loomed, and installed them into the car. Chased a couple bugs with the help of you guys, got the motor cranked up AND.........it locked up. Here we are a year later and we just did first start on the new motor and I'm chasing my next set of bugs. Nobody ever said learning to be a car guy was easy.....but I LOVE IT!!! The challenges ARE the journey.

Video of the engine running.

7 comments | We had a pretty exciting weekend. We did first start on the new motor!!! | By Nine Finger Wrenching | Facebook

We had a pretty exciting weekend. We did first start on the new motor!!!

www.facebook.com

 

[Nine Finger Wrenching]

I think you did the only test I’ve ever heard for a Ford gauge which is to ground the wire that attaches to the measured sending unit. If the gauge doesn’t go to the max range, it’s likely the actual gauge that needs to be replaced. But, with the reality the car is not stock, and as you say, it’s been converted to an older wiring harness, it might be that.

If it were mine, I’d buy the replacement gauge.

I appreciate it. Just need to hear a few other folks say this before I throw money at it. LOL

 

[Noobz347]

Maybe find yourself a 3-gauge pillar pod and put a [real] oil pressure gauge before fully attacking the Ford unit.

 

[General karthief]

You can take a 9V battery and wires and test the gauge from the back of the cluster, it should sweep to the high side when the wires are touched to the gauge connections.

 

[Nine Finger Wrenching]

Maybe find yourself a 3-gauge pillar pod and put a [real] oil pressure gauge before fully attacking the Ford unit.

Yeah those look pretty cool too.

 

[Nine Finger Wrenching]

You can take a 9V battery and wires and test the gauge from the back of the cluster, it should sweep to the high side when the wires are touched to the gauge connections.

Ahhh....now that's good stuff!! Thanks mane!!

 

[Nine Finger Wrenching]

7 comments | We had a pretty exciting weekend. We did first start on the new motor!!! | By Nine Finger Wrenching | Facebook

We had a pretty exciting weekend. We did first start on the new motor!!!

www.facebook.com

Here's a video of the engine running for the first time this past Saturday.

 

[Mustang5L5]

What year is the cluster in the car? Is it also an 87-89 cluster?

 

[85GTStangGuy]

From post #10...

.... I got a 89' dash and cluster to match. ....