Anyone know anything about Chevy trucks?

So, hell has recently froze over because I've got a Chevrolet sitting in my driveway. Made a deal with Hawkco on a 1989 Chevy 1500 pickup. This was the truck that quit on his uncle that day. We towed it up from his uncle's a few weeks ago and Terry had a local shop go through the fuel system, turned out to be the fuel pump that went out I believe. It's showing exactly 238,000 but I don't know how long it's been showing that because the odometer dosen't work. Has a 350/700R4 and runs and drives great, ice cold A/C.

Anyway, the truck hasn't been driven much since it was fixed, just a few miles around Terry's house at low speeds. The speedometer never worked, so we figured it just dosen't work at all. This evening was the first time it's really been ran any distance for quite a while (someone his uncle worked with towed it back to his uncle's house back in February and it just sat there for several months before we went and got it a few weeks ago). I was driving it home tonight on the interstate and after being on the interstate for about 15 minutes, the speedometer suddenly shot up to 65 and the truck kicked into overdrive and was cruising along nice. Then a few minutes later, the speedometer started bouncing around all over the place, anytime it went below 30 mph the truck would kick out of overdrive. It did that for about 20 miles, and the speedometer finally just went back down to 0 and stays there now. I can't find a speedometer cable, so I'm assuming this thing must be all electronic? Is there a speedometer sensor that can just be replaced?

Also, after being on the interstate for about 20 minutes, the brake light on the dash started randomly flashing. Then after it flashed randomly a few times, it got into this rhythm where it flashes fast 8 times and then on the 9th time it stays on for a couple of seconds and then repeats. It's doing that constantly now, even after I stopped to get gas. The check engine light also came on for a few minutes but went back off. The brakes work great.

I know, it's a Chevy.. but it's a deal I can't pass up and I've been needing a truck for a long while. It's a nice looking truck other then the clear coat peeling on the hood. I'll post pics of it tomorrow.

 

The speed sensor is on the fritz...or the harness to it is shorting out somwhere.The brake light is flashing a code...81.Does this truck have ABS brakes in the rear or all the way around???That could explain the brake light and the speedo problem(sensor is bad)at rear axle.The code 81 is as followes(according to my reference material)
81...QDM solinoid "A"(1st&2nd gear) current error.hope This helps you Jamie.

 

And I always thought Whacko liked you...

 

I'm not sure if it has ABS. Is there any quick way to tell? I assume there would be a module or something under the hood for it?

I'll let out a little known fact... all of the daily drivers at Terry's house are GM's. This thing won't be a daily driver, just a parts chaser and what not.

 

Black box attached to the side of the master.

 

I don't recall seeing any trucks (that year) that have them on all 4. I have seen them have all 4 on 4x's tho.

 

Yeah, driver's side in front of the brake booster will be a big gnarly block of a thing with wiring and brake lines going to it. That's the ABS unit. If you unplug the wiring, your ABS problems are over.

The speed sensor is in the tailhousing on the trans where a cable would normally go.

 

Excellent info, thanks guys. Just went and checked, and it does have ABS. The speed sensor isn't much at Auto Zone, I'll toss another in it tomorrow and see if that helps.

 

Also If you have any kind of ABS there should be a light on the dash(ABS) which lights up in yellow when you turn the key to the on position.If you have no light but do have the ABS module under the hood...the bulb is burned out or there is a short in the circuit...

 

Nope, the ABS light dosen't come on. When I turn the key on, I get the BRAKES light flashing, Check Engine Light, and another light that says CHECK GAUGES. I'm going to spend a few hours messing with it tomorrow afternoon, I'll check the bulb while I'm at it.

 

Find a wireing schematic for that intstrument cluster.I think you have an instrument harness problem and or a short in the ABS module harness.This could cause all your problems.good luck diggin around in that spaghetti Jamie.

 

Jamie, don't forget that there is Haynes manual and a complete, thick
Chilton's manual for that truck on the seat...next to the driver...where you were sitting.

 

Actualy I think the ABS sensor is in the diff on this one.

 

...Or it means you've unplugged it. The ABS light doesn't come on anymore after you unplug the module. Such was the case in my '91 Bravada anyway.

 

I believe you are right. In the top of the pumpkin, look for a plug with a harness on it...