Non-Rallye 1968 instrument cluster gas, temp, backlights dead. Limiter did not fix

[threewood]

Here's the thing - I'm getting excellent continuity, that I know. Haven't had anything fizzing or flickering out due to that - everything short of the two gauges get excellent power, and the IRV4 always lights up too.

All the flashing has been definitely been from the limiter.

-Kurt

Wiggle up under there with the key on and probe the ivr center prong for 12v, then probe the right prong for 5v. If you have done the solid state conversion it should be steady. If you have 5v at the ivr, probe the 5v studs to the coolant temp / fuel gauges. If the reading is solid start back probing the the sender stud on the back of the gauge to the pin connector for continuity. You can even attach a long lead from this stud and quickly ground to get movement on the gauge.

 

[cudak888]

Wiggle up under there with the key on and probe the ivr center prong for 12v, then probe the right prong for 5v. If you have done the solid state conversion it should be steady. If you have 5v at the ivr, probe the 5v studs to the coolant temp / fuel gauges. If the reading is solid start back probing the the sender stud on the back of the gauge to the pin connector for continuity. You can even attach a long lead from this stud and quickly ground to get movement on the gauge.

I have both clusters out of the car at the moment, but can feed 12V in from my model railroad power supply and check them. Will do right now.

-Kurt

 

[cudak888]

Wiggle up under there with the key on and probe the ivr center prong for 12v, then probe the right prong for 5v. If you have done the solid state conversion it should be steady. If you have 5v at the ivr, probe the 5v studs to the coolant temp / fuel gauges. If the reading is solid start back probing the the sender stud on the back of the gauge to the pin connector for continuity. You can even attach a long lead from this stud and quickly ground to get movement on the gauge.

I did a few bench tests, and got either 10v or 1.4-1.7v at the output prong of the IRV4. I know that has to be wrong, and I know there's something else wrong, so before I go any further, I have to ask the following:

I keep getting hung up on this diagram when trying to wire the car up:

First off, according to my car AND the factory 1968, 1969, and 1970 wiring manuals, those wire colors are wrong. So be it, the functions are still in the same place.

EXCEPT - isn't that "ground" plug really switched positive 12V power into to the cluster and the limiter from the ignition switch? It also feeds the oil and brake indicator light bulbs, and according to the wiring diagram, both the oil sender and the brake switch are essentially on/off grounding switches, and should be negative 12V.

-Kurt

 

[cudak888]

EXCEPT - isn't that "ground" plug really switched positive 12V power into to the cluster and the limiter from the ignition switch? It also feeds the oil and brake indicator light bulbs, and according to the wiring diagram, both the oil sender and the brake switch are essentially on/off grounding switches, and should be negative 12V.

I just answered my own question. And I think I answered a few others.

If the factory manual here accurately reflects what Joe Union of the UAW shoved into my dashboard between beers back in 1968, my dark blue w/stripe wire - which is supposed to be my +12V switched ignition - is currently sitting on the post for the e-brake/brake failure warning light, based on the forum diagram in the previous post. And the brake failure/e-brake warning light is on the switched ignition plug.

The only things fed directly by switched ignition are the oil warning light, e-brake light, and limiter. And since the brake light doesn't give a hoot which way the polarity is, it comes on anyway. But the limiter does give a hoot. A really big hoot. <Insert your worst Hooters joke here>.

<Now insert long silence followed by some vaguely amusing verbal vulgarity here>

In other words, the correct routing should have the blue-with-stripe wire providing +12V switched ignition to the following part of the board, and the black wire providing -12V/ground to the e-brake light:

I don't know who drew up that old cluster diagram that circulates here on the forum, but - with no personal offense meant to the fellow who created it - it's starting to look like 75% of it was drawn by looking at the harness upside down, 20% filled in with vague assumptions, and the remaining 5% completed by guesstimated bullshit.

Oy, what a night...

-Kurt

 

[miller]

Glad to hear you found it, Kurt! Good show.

 

[bigmanjbmopar]

Wow you have done a lot of work with this, now go buy the modern upgraded circuit board from Charger specialties he sells on ebay too. believe me we have all gone through this those old ckt boards were not meant to last 45 years I tried to rehab 2 of them and finally said screw it and got the modern version thank god they make one! I did a video on youtube about how the gas gauge and sender works and how to test it look it up. for the temp gauge its easy get a new gauge from classic ind or goods used one from ebay and replace the sender in the block for peace of mind. also on the fuel the stock sending unit responds very slowly so be patient waiting for it to go to full takes 30 seconds or more sometimes. anothing thing the cluster itself grounds itself to the dash frame make sure all the screws are tight when bench testing run a ground to the mounting screw holes for testing.

http://chargerspecialties.net/circuit-boards.html

 

[cudak888]

Wow you have done a lot of work with this, now go buy the modern upgraded circuit board from Charger specialties he sells on ebay too. believe me we have all gone through this those old ckt boards were not meant to last 45 years

I'm lucky enough to be working with one really nice original board, and another that cleaned up very well. In comparison to modern PCBs used in household electronics, I dare say these 45 year old monsters cooking (or freezing) under steel dashboards surrounded by any kind of weather just might prove to hold up better than when the new stuff reaches the same age.

Plus, I've found that 1/16" brass K&S tube is an ideal repair material for missing pins. I replaced the top one here and repaired a few of the originals (pic in a moment):

-Kurt

 

[cudak888]

Report from this morning:

SUCCESS! Flipped the blue/white and black wires, and for the very first time, I got to see the gas gauge (barely) sweep up a few millimeters. (It works!). No action at the temp gauge (I have verified continuity with it under the hood), but it was a cold start. Only ran the car for about 30 seconds anyway.

And so no other DIY'er ever winds up scratching their heads over this (mainly thanks to that shitty diagram...that I've helped to circulate even more), here's my contribution to de-mystifying the wiring for these non-Rallye 1968, 1969, and 1970 instrument clusters - though YMMV on the '69 and '70s. Approach with caution, at any rate:

(Click here for the full-size version on Flickr)

-Kurt

 

[cudak888]

FYI - tried to fire up the original tach today when installing the new cluster. Turns out the USPS dented the rear in transit which caused the fiberboard insulator to crack. Shorted out; car would crank but not fire.

Disconnected it, everything was OK. Pulled the cluster (getting to be a bloody expert at this; can plug in and pull off anything and everything blind now), removed the tach, disassembled it, and alligator-clipped it to the tach lead and 12V switched ignition and ground.

Dead.

Did some searching; some seem to say the factory tach won't work with electronic ignition, others say it will. I'm running a Ford TFI e-core coil with GM HEI, so it's a bit more like an MSD setup than the factory Chrysler electronic ignition box too.

Now the question is...another $75 for RTE's PCB, or my 3D printed tach replica and live with the two screws in front holding the $8 China tach in place?

EDIT: Did the RTE quick-as-you-can 12V test. It still operates. Probably going to take the additional $75 plunge. Yech.

-Kurt

 

[cudak888]

Just finished swapping the Chinese fuel sender with a factory original (from forum member 68 Charger - great guy!). Had to fix the nylon isolator on it, but I'm pleased to report the following:

It works - correctly!

In the end, it turns out this was a quadruple whammy. The problem was caused by all of the following issues:

• A miswired dash cluster connector
• A fried gas gauge (due to the miswired dash cluster)
• A fried limiter (due to either the miswiring, or just by virtue of the originals being crap)
• A lousy Chinese sending unit.

There's one thing for sure - this car has not let me off easy!

-Kurt

 

[beanhead]

Thanks for posting the final results!

 

[Billccm]

You've done a great service to the FBBO community!

How about an idiots guide to removal and installation of the entire cluster? Have any tips, or tricks?

 

[cudak888]

You've done a great service to the FBBO community!

How about an idiots guide to removal and installation of the entire cluster? Have any tips, or tricks?

Oooh. Removal guide. Tough for anyone who hasn't pulled one out before.

That said, it's a royal pain:

1. The plastic finishing plate below the steering column has to be removed, along with the lower switch panel that fits inside the lower dash pad.
2. Twist your wrist under the switch panel and try to disconnect each of the lower switch panel plugs before unscrewing the panel.
3. Even then, the panel will probably stick if the pad is warped (most are), and will require some wiggling to set free. Some thin tongue depressors may help. Be particularly careful not to get the dimmer switch (which sticks out quite a bit in the back) hung up on the dash frame, or you'll probably crack it.
4. Once the lower switch panel is out, you'll see three screws - now visible in the gap - holding the top half of the pad down on metal tabs. Remove them.
5. The pad STILL will be too tight on the dash to allow cluster removal. Twist (and I MEAN twist) your wrists under the dash to see if you can feel each of the speed nuts and nipples holding the pad in place. (Don't enjoy this too much, that's what your wife is for). I don't remember exactly what the speed nut size is, but it's easiest to take a socket and spin them off by twisting the socket in your fingers. Each of these speed nuts are also in a lousy location, and here's a photo (sorry, took it from eBay) of where they are. You really only need to back off the three to the right of the ignition switch opening. Also, you should be able to get away with just loosening them:
   
6. Now that you've accomplished that miracle, stick your hand up the back of the dash - from the left side of the column - and feel around the back of the cluster. Find the box shape at the center, and the speedo cable. Squeeze the release lever and pop it off. Then move straight up and you should feel the round connector at the back that connects the car's wiring to the cluster. It will be tight. Pull it out straight and firm, do NOT twist or make side to side motions unless you want to break or loosen one of the connector pins.
7. Back on the face of the dash, undo the two screws that hold the two upper tabs of the cluster to the top edge of the dash.
8. Carefully pull the top of the pad down. You'll see four screws holding the cluster to the dash. Unscrew them all, and be careful cranking on the one near the radio, as the dash frame can be fragile and crack-prone in that spot.
9. If a column-shift automatic, engage parking brake (it better work, if not, chock the wheels), and put the car in first gear.
10. Use masking tape to hold the pad top squeezed down. Grab the cluster, and carefully pull it towards you while rotating the face downwards just slightly.
11. Soon as it's free of the dash, angle the cluster so you can undo the nuts on the ammeter terminal connections on the left side of the dash.
12. If you have a tach, move to the right, undo the lamp, then pull the spade and press-on connectors.
13. Keep moving the cluster forward/rotate. Cluster should now be free. Slide to the left of the column and put to the side.
14. Return car back to park.
15. Cuss car
16. Cuss instrument cluster
17. Cuss dash pad
18. Have a beer
19. Reverse all instructions to reinstall, only repeat 15-18 at both start and end.

-Kurt

 

[Billccm]

Bravo. I'm looking forward to this job eventually.

 

[cudak888]

Bravo. I'm looking forward to this job eventually.

Best of luck. It's a major PITA. Not to actually pull it and reinstall it, but to take everything out that's in its way. Mopar made NO attempt to make this easy when it could have been made quite simple.

One particular suggestion - connect the ammeter (or voltmeter, if converted) first. If doing the conversion, make the leads about 5" longer than necessary to allow for ease of installation. Then install the cluster and connect the rest blind, with the cluster installed.

If you can clock the connector for the PCB correctly by feel alone, it'll be easier on your dash pad and steering column than resting it there - rags or otherwise.

-Kurt

 

[threewood]

First step in cluster removal should be remove driver side seat.

 

[cudak888]

First step in cluster removal should be remove driver side seat.

Not advisable if it's a bench . Not unless you have a helper, anyway.

Never felt it necessary to remove the bench though, even though they sit higher and farther forward than buckets. Found it beneficial to sit on it while pulling the cluster, and most of the under-the-dash work was accomplished by kneeling from the outside.

Oh - one interesting note - if you only need to replace your limiter, it's possible to do it without removing the cluster. You have to familiarize yourself with the shape of it by feel, but once you've found it under the dash, it's possible to swap it in under 30 seconds.

-Kurt

 

[cudak888]

I realize I didn't really run through the whole debacle with the sender in this thread, but I needed a place to put up these photos of the factory sender that I ultimately repaired for the car. Drilled out the rivet, installed three nylon washers (one thick one in the hole, and two larger flat ones at each end) with either a 2mm or 2.8mm (don't recall which worked) RC car hex screw and locknut to hold it all together. Also put some solder in the worn-out hole on the finger that rides against the rheostat:

-Kurt

 

[miller]

Yeah, pretty much what I did on mine. Combined parts from two senders, to get one good. So far, good.