Another Gauge Cluster Question or 3

[Splandman]

I am trying to get a truck ready for my daughter who turns 16 in July. I offered to buy her several different vehicles (a lot of the $$ is hers that she earned) but she insists she wants my daily driver truck. There are several things wrong with it that didn't bother me so much with me driving it but I want it correct for her.

Since I bought the truck it's only had about 1 of the gauge lights working. Also, someone had installed some pod gauges and mounted them under the dash. I didn't like them and wanted the originals used.

Once I took out the gauge cluster to install the bulbs, I noticed it had 3 of the ears that are mounts broken. I also noticed that green box for the cruise was missing. I bought a cluster off of Ebay and am now trying to install it. Here are the problems so far:

I plugged the gauge cluster in and the temp gauge goes all the way to the right (260 degrees) and stays there.

I don't know where to find the wire that would lead to the oil pressure gauge. I was hoping they just took it off and hooked up the one going to the aftermarket gauge but I am not seeing it.

I have no idea where the green cruise box things plugs in.

It does not appear that the wires to my plug were cut anywhere so I am assuming they ran new wires to run the gauge cluster. I found what I think should be the water temp wire with a black fitting on the end laying on my intake manifold. I put it on but got nothing. I think the black end that slides on the prong coming off the thermostat housing is bad but not sure.

Here are some pics but they suck. Was holding my phone wrong I guess.
The second pic is the one showing the wires the previous owner used to run the aftermarket gauges.

 

[PrairieDrifter]

Your temp gauge is grounded if it's pegging out at 260 and the oil pressure sending unit should either be on the side of the block or just behind the distributor

 

[Splandman]

Looks like the connection on my sending unit is broken off.
Also, does this look like the wire that would go to the sending unit.

 

[PrairieDrifter]

That looks the like the one! That clip should just slide onto a peg on the temp sender, the wire is green which looks like that's what you have

 

[Splandman]

Thanks, I will have to get me a new temp sending unit and see if that does it.

 

[PrairieDrifter]

Unless the wire is grounded out somewhere it should work, if the guage is any good in the first place ha

 

[83K5]

In your first picture there is the main cluster connector and another light connector, what is that light connector for? Also my oil pressure gauge pegs out as soon as the engine starts and the wire I have connected to it has a rubber connector on it like you said your temp gauge has. So what is the correct wire for the oil pressure sensor.

 

[chengny]

In your first picture there is the main cluster connector and another light connector, what is that light connector for?

It's hard for me to tell (I'm color blind). But if the leads into the socket are brown and white, that is most likely the socket for the 4WD indicating lamp.

Also my oil pressure gauge pegs out as soon as the engine starts

The gauge may actually be reading correctly. To test the circuit:

1. Turn the key to just the RUN position and stop there for a moment. Note the pressure as indicated.

2. Move the key to START. Watch the gauge as the engine cranks and fires up.

Determining the results:

1. If the gauge pegged high with the key in just the RUN position and without the engine running (i.e. zero oil pressure), there is a problem with the sensing leg for the gauge. It is either grounded or broken/disconnected. I'd have to think for a bit to say which for sure. But I would bet it's disconnected. I don't think you have the correct lead connected to the sender (see the last paragraph).

2. If the oil pressure gauge indicated about 15 psi (or anything less than pegged high) with the ignition switch in RUN, and only pegs high when the motor comes up to speed - the gauge and wiring are okay.

There are two remaining reasons why the gauge pegs high when the engine cranks/fires:

1. Your oil pressure may actually be very high (60 psi or above)

2. The sender may be out of calibration.

To determine which is the problem, check the actual oil pressure with a mechanical gauge and compare readings:

1. If there is a large difference, the sender is out of calibration. Replace it.

2. If the test gauge also indicates 60 psi or higher – the entire oil pressure indicating circuit is functioning correctly. Your engine oil pressure is very high.

and the wire I have connected to it has a rubber connector on it like you said your temp gauge has. So what is the correct wire for the oil pressure sensor.

The housing for the coolant temperature connector (in the discussion and images above) is hard, heat resistant plastic and rectangular in shape.

The housing of the connector that attaches to the oil pressure sender is a round boot made of pliable rubber. It has a lip that snaps over the ridge on the sender. Both the terminal on the sender and the actual connector within the boot are off-set from center:

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The sensing leg of the oil pressure gauge - the one that connects to the sender - is tan. This is true on any SBC installed in a 1973-1987 C/K truck.

 

[PrairieDrifter]

It looks like brown and white wires from what I can tell.

 

[Splandman]

In your first picture there is the main cluster connector and another light connector, what is that light connector for? Also my oil pressure gauge pegs out as soon as the engine starts and the wire I have connected to it has a rubber connector on it like you said your temp gauge has. So what is the correct wire for the oil pressure sensor.

I believe chengny has it correct when he said it was my 4WD indicator lamp, which reminded me I forgot to plug that back in before setting the cluster back into place.

I put a new temp sending unit in but still nothing. My black rectangle connector is partially melted in a spot and looks a little crushed. The green wire it's attached to runs along with the wire that goes to the ac compressor and then clips into another black clip near the center of the engine compartment along the firewall.

I cleaned out the rats nest of wires the previous owner had run through the firewall to run the aftermarket gauges. Everything was going fine til right at the end. I now have no power to the stereo or the a/c heater controls, I may have cut a ground wire. Not sure.

 

[Splandman]

Here's a pic of the connection

 

[PrairieDrifter]

Do you have the ground going to the firewall from the back of the head?

 

[Splandman]

Do you have the ground going to the firewall from the back of the head?

Just went out and checked. There's one on the passenger side firewall right behind the head. I just reached out and grabbed it and it's broken completely off.

Thank you very much, that fixed it. I didn't even hook up a proper ground, just took some alligator clips, put one end on the broken ground strap and the other on the alternator bracket and the gauge worked immediately. I will get a correct ground hooded up tomorrow.

 

[PrairieDrifter]

Just went out and checked. There's one on the passenger side firewall right behind the head. I just reached out and grabbed it and it's broken completely off.

Thank you very much, that fixed it. I didn't even hook up a proper ground, just took some alligator clips, put one end on the broken ground strap and the other on the alternator bracket and the gauge worked immediately. I will get a correct ground hooded up tomorrow.

Perfect! That ground can cause all sorts of weird electrical issues and is often overlooked or people don't even know about it.

Did that fix your stereo problems also?

 

[Splandman]

Perfect! That ground can cause all sorts of weird electrical issues and is often overlooked or people don't even know about it.

Did that fix your stereo problems also?

I spoke too soon. It didn't fix it, but changed the way it acted. Now when it's running the gauge stays around 120. When the key is turned on but truck is not running, the gauge is around the 12 o'clock position.

Something Rich Weyand said in another thread makes me wonder if I have the wrong sending unit. I know the prong on this one that you connect to is too wide to fit in that stock plastic connector.

I still don't have it grounded properly either. I will fix all that and see what happens.

The stereo was nothing more than me yanking the power wire out of the fuse box when I was cleaning up other wiring the previous owner had put in there.