1991 C1500 in Florida

[FLGS400]

Took the truck for a drive tonight and bed in the brake pads. Brakes work great!

I'm also happy to report that now the odometer works, too. The only odd thing was, when I was sitting at a traffic light, with the turn signal on, the volt gauge was jumping up and down to the beat of the turn signal relay... When I pull the cluster back out again, I'll check all the grounds for everything.

I got the interior panel clips in from Amazon. They are much narrower than the stock ones, but they will work with a little massaging. I'll try to post up a picture tomorrow night comparing them.

 

[FLGS400]

This past week I've worked on the truck a little here and there. Polished the gauge cluster lens, cleaned up gauges, re-soldered the ground contact on my replacement cluster and added a separate ground wire for the case, installed white LEDs in all the light sockets (and bench verified they work), put the gauge cluster back in the dash, and rigged the collar that moves with the shifter for the gear indicator. 1 of the tabs is broken off of it, so I made a little metal bracket to go behind it and screwed that into the plastic sleeve and the metal collar for the shifter. Huge light difference with the LEDs and all dash lights working. Really makes the moonie gauges pop!

Right now I'm having 3 issues....
1. The oil pressure gauge is constantly pegged with this cluster, even though I swapped in the working gauge from the other cluster. Need to check the sending unit...
2. I suspect that the temperature gauge reads about 25-30 degrees low.
3. I'm having a tough time finding a convenient place to mount one of my aftermarket Autometer tach. May have to mount it on the bottom of the gauge surround bezel. I just hate to drill more holes in it...

I forgot to verify ground on pin B11, in the plug. I'll have to pull the cluster back out and do that, before I put the bezel back on and mount the tach in there. I could unpin B15 and use it to signal my tach, too.

I'm considering mounting an Autometer mechanical oil pressure and temperature gauges, in cups, under the dash. I have the gauges already, just need to get the copper line kit and brass tee (for the oil pressure port in the block) for the oil pressure, and the cups for both gauges.

 

[FLGS400]

Tonight, I cleaned up the grounds under the hood. The wire from the battery to the fender area got new connectors, as did the 2 small wires on the intake. Those are supposed to go to the thermostat housing bolt, but somewhere along the line, someone bolted them to the same intake bolt that the negative battery cable bolts to. That connection at the intake bolt was pretty grungy. Also got the ground near the power distribution block (firewall), and the ground connection under the heater hoses (also on the fire wall). That one was pretty rusty... It could use the ground straps replaced, but for now they are still intact and I don't see how the hell you can get to the bolt on the back of the head, for the top one!

Maybe when I trouble shoot the oil pressure sensor, I'll see if I can get a better look. That sending unit looks like a PITA to get to, also... I may have to climb into the engine compartment. LOL

Well , that's it until Sunday night or Monday folks.

 

[Sean Buick 76]

I’ve personally never found the gauges on these trucks very accurate or reliable.

 

[FLGS400]

I’ve personally never found the gauges on these trucks very accurate or reliable.

Honestly, all I really care about is the fuel gauge, speedometer, and odometer. The oil pressure gauge is the only one that doesn't, at the moment. It's definitely getting the Sport-Comp gauges at some point, though.

 

[Scooterwrench]

You may have to pull the dist. to gain access to that OP sensor. Roll the crank up to #1 TDC and match mark the the reluctor and pickup coil with a sharpie. Line up those marks when you drop the dist. back in and you should be dead nuts in time.

 

[FLGS400]

I got back out to the garage tonight and trouble shot the constantly pegged oil pressure gauge issue. Climbed into the engine compartment, unplugged the sender, and grounded the tan wire. Turned the key to on and the oil pressure gauge went all the way to the left. So it appears that the gauge and wiring are OK and I need a new sending unit for it.

I got the old one out, without pulling the distributor, by unplugging the distributor connectors, gently moving the adapter to the right a wee bit with a 3/4 crows foot, then used a combination of a small pipe wrench, a small pair of channel locks, a medium pair of channel locks, and a boat load of patience!

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I think I'm just going to replace that sender for now. I was going to add the mechanical Sport-Comp gauge too, but I would have to order more stuff (like a cup and line kit) to install it, and I really doubt there is enough room for a tee in there. Plus I think I'll still need the sending unit so the fuel pump activates... correct?

I was reading a post on a thirdgen.org about there being another oil pressure port above the oil filter. I may use that one in the near future (if it is indeed there on this 5.7) for the aftermarket gauge. At the same time, I'll install the matching water temp gauge.

Oh... I did find a couple pictures from last Tuesday night when I went trough the used gauge cluster to change the mileage on the odometer and put the LEDs in it.

I was actually able to take the row of numbers out of my old odometer (just the odometer side), and install it in the working odometer in the used cluster. Was really easy to do!

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I also used just a dab, of a light, plastic friendly lube on all the gears.

Here's the circuit board from the used cluster. It is in prefect condition!

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That's it for tonight. May be a few days before I get back on the truck again. This week I have to give the GS400 a going over, to get it ready for a 420+ mile road trip next weekend.... weather permitting.

 

[Scooterwrench]

I had to add a second sender unit for the aftermarket gauges in my truck. I drilled and tapped the existing adapter for the gauge sender. May work for you too.

 

[Jimmy D]

Took the truck for a drive tonight and bed in the brake pads. Brakes work great!

I'm also happy to report that now the odometer works, too. The only odd thing was, when I was sitting at a traffic light, with the turn signal on, the volt gauge was jumping up and down to the beat of the turn signal relay... When I pull the cluster back out again, I'll check all the grounds for everything.

I got the interior panel clips in from Amazon. They are much narrower than the stock ones, but they will work with a little massaging. I'll try to post up a picture tomorrow night comparing them.

Velcro FTW on that back cab panel.

 

[FLGS400]

I had to add a second sender unit for the aftermarket gauges in my truck. I drilled and tapped the existing adapter for the gauge sender. May work for you too.

That's a idea I didn't think of, thank you!

Velcro FTW on that back cab panel.

Yeah, I'm looking at using that picture hanging stuff that is like Velcro, especially in the center part of the back panel. Somehow I ended up with a bunch of it...