The Powertrain Diagnostics Procedures manual calls for a DRBII scan tool. They seem to be pretty hard to come by.

There's one on eBay. I'd like it, but the wallet is pretty dusty about now.

Is there an OTC, Snap-on, or laptop emulator that works?

 

The older snap on bricks/ MT2500 could read our trucks. OTC doesn't make anything. I have not found anything laptop to work with our trucks. A Pro-Link 9000 will read our trucks. But its software does not support 93 models and no updates for that eather. Pro-Link stopped support of that model of scanner in 92.

The pickings are very slim. The last Star link scanner I noticed for sale would put you into sticker shock. Star link is a Dodge dealer scanner.

 

One more reason to like the early first gens

 

It's possible to debug these with common sense and a meter. It would just be more convenient to use a scan tool to watch things as they happen, or manipulate things, like the manifold heater relays for diagnostics. It's not quite worth $900 to me, though.

Most of the world was going ODB about that time, but the Detroit crowd had their own ideas, widely variant and obsolete when released.

 

Yea that's why I have a 2014 model now.

There are times where a scanner is the only thing that can find a problem. I went threw that a long time ago. I had problems with my CC dropping out. I could not find anything wrong. I went threw the CC system many times. I gave up and took it to the dealer. The tech had to drive the truck for about 3 days back and forth to work to find the problem. He was watching a single circuit at a time on the star link. The end problem was the brake light switch. That switch tested good on a meter many times. The tech did a meter test also. It wouldn't drop CC on a bump. It was just a random drop out. The tech cut the switch apart. It was corrosion and badly worn contact arm. Plus some of the corrosion was shaped in a ball. It just floated around the inside of the switch housing.

 

That would explain why my CC has basically quit, by brake light switch is ailing and I stupidly didn't put 2 and 2 together. My "resume" quit a long time ago so I have a Dak clockspring waiting to go in, and I have a new brake light switch waiting too.

 

I just fixed resume in mine. Got the actual switches (all $4.00 worth), and a clock spring all lined up and went in. Preliminary circuit test identified a bad switch. When I went into the plastic thingie to replace the switch, I found a small finger of plastic was broken. put a cap from another defective switch on it and put it back in service.

So don't assume it's a clock spring until you do some testing. It's pretty easy. Remove the horn button and get to the connector. One pin is powered with the ignition key. 2 more light when you set CC to on. One of those blinks off with the reset switch. The other one blinks on with the resume switch. Ground a test light to the horn ground lead that's hanging in your way and have at it.

If you need the actual micro switches, I have all 3 of them on hand.

 

Thanks for the tips. I may buy a switch or two off you!

 

Mark the brake light switch is a double switch. One side is brake the other side
CC disconnect. My brake light side was perfect. The CC side was the problem. I even drove it for a week or so with a meter hooked up to watch for problems. It didn't show anything. The star scanner did. But it took the tech a few days to see it even on the scanner. My meter and his scanner was to slow to catch the signal drop for the fraction of a second it took to drop CC.

 

My brake lights started coming on a lot by themselves, and the switch isn't loose.

 

Perhaps you recently put in a vacuum booster.......ie A1Cardone. There's a snap ring or something inside of those things that's supposed to keep the push rod from pulling out past a certain point. That feature is used as the return stop on the brake pedal. If it fails, the pedal pushes the brake switch out of adjustment, and the lights then stay on. Both A1.... boosters I got from NAPA last year failed immediately.

BTDT got the t-shirt.

 

LOL MY 1990 is somewhat simpler.

 

That high tech voltage regulator on the firewall?

 

Even a good volt meter doesn't tell the whole story. Mainly because they don't put a load on the wiring. The older they get, the more susceptible the wiring is to failure. Even though your ohm meter says it's good, the wiring has lost its ability to carry a load. Corrosion, vibration, and heat weaken a wire, switch, or connector over time. If you notice ground problems, guaranteed it is only the beginning.

 

Yeah, that too