Rally gauge cluster installation (1st gen)

[Cartman2112]

I have a chance to purchase a rally gauge cluster complete with the console gauges. I am currently trying to find out if the donor what the rear axle ratio of the donor truck was so I won't have to deal with speedometer issues. My question is, did the first gen trucks use a unique wiring harness for the rally cluster or did they use a common harness with the wires just unused? If a unique harness was used what should I expect to have to do to correctly connect the gauges? My truck is a 1985 Ram 50 custom, 2.0L, automatic....bone stock...

Thanks!!

[boozehero]

I installed a tach speedo cluster in my 79. I had to run a tach signal wire from the coil. I searched for a while for a factory installed lead, but there was none.
I also have the rally cluster and there are no wires for it in the harness. I will have to add wiring. The oil pressure sending unit is also different for the OP gauge too.

[Cartman2112]

That's what I figured. I've got a factory service manual on order. Maybe that will help me with some ideas. thanks for the response..

[boozehero]

I have the factory tech manual specific to the year of my truck. It has a wiring diagram in the back of it - yours should also.
It shows the "W" and "U" engine options. The W engine is the 2.6 IIRC and those trucks had a tach and the gauges.

When I installed the tach cluster, the pins are all the same for the unit, but the tach signal wire wasn't there. I ran a white wire (correct color) for the tach from the negative side of the coil to pin #7 which had no wire. I traced the printed circuit on the tach board and it went to pin #7.
So... Tach works properly.

When you receive the tech manual, you will also notice that there is a white (I think I remember) wire on the alternator which triggers the warning light. If I'm not mistaken, that will have to go to the ammeter hot side (white and brown wire) the other side of the gauge is grounded.

You can also find the pin on the gauge cluster connection that goes to the oil pressure warning light and use it for the OP gauge lead.
The OP sending unit is specific for a gauge. Your stock sender is either on or off. It goes on at about 4 LBS of oil pressure or less. It will peg the gauge when the engine is running.

Anyway, good luck and post pix if you can.

[Cartman2112]

Thanks for the information. It certainly give me a pretty good idea of where to start. I received my service manual in the mail today and took a look at the instrument cluster wiring diagrams. It appears, that for 1985, the U (2.0L) engine was not available with full instrumentation, only the W and TBD engines.I'm hoping that this difference does not cause any complexities in the wiring. I'll do some more research and see if I can find any more information.

Thanks for all of your help and I'll keep posting my progress.

[Cartman2112]

Damn, I must either be blind, dyslexic, having flashbacks or a senior moment (just turned 63 last week). It just clicked that your truck is even older than mine!! I know it says 1979 but for some reason my addled brain kept seeing 89. Wasn't till I saw your pics that it finally dawned on me.... God help me when I start on this wiring...

[boozehero]

^^^ Don't worry. Your brain is still working just fine!
The wiring is pretty simple. There is only one wire for the tach and the oil pressure and ammeter aren't much harder.
I can help you out if you need it. I can post pix too.
BTW, I'll be 68 very shortly.
If I can do it, you can too!

[Cartman2112]

Well, as soon as the parts come in I'll see what I can do!!!!

[Cartman2112]

Well, they were finally delivered yesterday. They look like they are in good shape. One tab on the instrument cluster was broken in shipping but I'll just epoxy it back on. Not going to pursue this until I can build a little console to mount the gauges in. I also have another instrument panel bezel on order so I can carve it up to mount a stereo system in.

[boozehero]

A little late on the reply...
The speedo is in MPH, yes? Mine only goes to 85 MPH and this pic shows 120 MPH (?!)
I need one of those since my truck (some modifications) easily goes past 85, like very easily. I'm guessing it is capable of 100 - and being optimistic - 105 MPH.
Did you manage to install your cluster?
You probably already know that there is a console on some of these trux that has the mounts for the OP and ammeter gauges. There is a tab welded to the floor under the floor mat/carpet that you screw the console to. It also bolts under the dash lip. Its an easy install.

[Cartman2112]

Here's to another late reply...

I've haven't had a chance to work on the truck due to some back problems I'm having. Can't really be crawling under the dash to run wires when I can hardly bend over. Had an MRI done and waiting on the results.

Yes, the speedo is MPH. I can't remember what year they did away with the 85 MPH unit. My stock dash currently has a 120 in it.

I have seen pictures of the consoles you are talking about and have searched for them. I have found a couple but they wanted an arm and a leg for them. Thanks for the info on the floor tab. I've made some measurements and sketches to try to design my own (when I can get moving again)!!

Also picked up a dash panel that I can carve up for a head unit. I want to keep the original one as is along with the old AM radio.

[geezer101]

Be aware that you may (well, probably...) have issues fitting an aftermarket single DIN head unit into the dash. It's the steel dash frame behind the bezel that will foul it. No biggie, you can modify the dash frame to clear if you can't get it to fully seat into the dash correctly. If you opt for a fancy mechless head unit, you might not need to fettle anything but you gotta have tunes!

[Cartman2112]

The head unit I have is a cheapo AM/FM USB/SD/BT only unit. So it's one of the shallow sets. Planning on wiring it into a nice amp if I ever get back to where I can work on it. I've already been into the dash and even this unit needed some mods. I still had to cut out one piece of the dash frame and take my Dremel grinder to the unit itself to trim one of the heat sink fins. What a PITA!!

[geezer101]

Just run the RCA cables and the amp remote trigger wire and roll it up out of the way until you get around to installing the amp (tuck it up behind the glove box and tape it in place) It'll save you having to pull the head unit to connect it up. Make sure the end of the amp trigger wire doesn't have an exposed end on it or it'll roast the power supply in the head unit. You could get fancy and install a power antenna inside the fender if you are running a telescopic antenna. I managed to get one to fit in there and most aftermarket head units have a power antenna wire in the harness.

[Cartman2112]

I was up in the attic and found this blast from the past. If it still works I may hook it up to my cheapo head unit and some speakers and see how it sounds before I do the install. It's rated at 100w per channel. I used to have it in an old Dart I had.

[Cartman2112]

@boozehero - After doing some research it appears to me that 1984 was the first model year that had to 120MPH speedometer. Someone please correct me if I am wrong.

[geezer101]

Oh man, a 10 band graphic equaliser. Very cool for a retro piece of audio gear but they are crappy lol. It's output is probably more like 10-15w per channel. I've kept one of these weird car audio accessory units but this one was different. It's a surround sound staging amp that lets you alter how the speakers are phased. Have to admit that this cheap piece of junk really sounds amazing - it'll turn the inside cab of a car or truck into an ampitheatre. Just freakish how it does it (you have to manually adjust each channel to get it to phase the way you want it). The adjusting knobs are really crackly and a friend who has messed with them said when the internal protection fails, it'll pump 12vDC straight through the speakers and turn them into cigarette lighters

[Cartman2112]

OK, here's one for you. I can't find them now but somewhere around here I've still got a set of the old 6x9 Mindblower speakers. A buddy of mine had them installed in his '68 Charger. When he got rid of the car he gave them to me. I happened to stumble across them a couple years ago. The cones in the speakers are in surprisingly good shape considering their age but I don't have the bass boost controller that mounter under the dash. If I find them I'll post some pics on here.

[geezer101]

They are actually a sought after period correct part for guys wanting to do a 70's car resto from what I've found in a search. But... they apparently sound like garbage compared to other 70's offerings like Jensen, Pyle, Alpine and Sony. The audio guys all admit the Pyramid speakers were low end quality.

[Cartman2112]

Hell, maybe I can sell them for some ungodly amount on ebay...

[Cartman2112]

Quick question. What sending unit did you use for the oil pressure gauge?

[tortron]

I have one of these in mine with centre console gauges
https://www.rockauto.com/en/moreinfo...dRlbyKbA%3D%3D

mine are the round style ones however, but i dont think they would have used a different ohm/sweep

[RatsoMX]

I have the factory tech manual specific to the year of my truck. It has a wiring diagram in the back of it - yours should also.
It shows the "W" and "U" engine options. The W engine is the 2.6 IIRC and those trucks had a tach and the gauges.

When I installed the tach cluster, the pins are all the same for the unit, but the tach signal wire wasn't there. I ran a white wire (correct color) for the tach from the negative side of the coil to pin #7 which had no wire. I traced the printed circuit on the tach board and it went to pin #7.
So... Tach works properly.

When you receive the tech manual, you will also notice that there is a white (I think I remember) wire on the alternator which triggers the warning light. If I'm not mistaken, that will have to go to the ammeter hot side (white and brown wire) the other side of the gauge is grounded.

You can also find the pin on the gauge cluster connection that goes to the oil pressure warning light and use it for the OP gauge lead.
The OP sending unit is specific for a gauge. Your stock sender is either on or off. It goes on at about 4 LBS of oil pressure or less. It will peg the gauge when the engine is running.

Anyway, good luck and post pix if you can.

I appreciate all the helpful information you've supplied us on this subject. I'm also in the process of adding the console gauges and the Tach/Speedo cluster to my '84 4WD D50. Fortunately I've saved quite a few NOS parts that I purchased back in the early '90's. But, I was never quite clear on how to accomplish the conversion.

One thing I wanted to ask, do you know what would be involved in converting over to the intermittent windshield wipers? I had them in my 2WD '84 Sport, and it was so much nicer than the cheapo two speed wipers currently in my 4X4.