So dad bought his 6th 1st gen over the weekend. A 91 D250 reg cab that is totally rust free. A Texas truck just about all its life. Its an odd ball as its never been tweeked for power. Hell it still has the original exhaust on it. Very rare for a northern truck. He paid $1,250 for this truck. Very fair considering its rust free condition. The catch is I am going through and repairing the years of neglected and past owner issues. It did not run. A simple lift pump and it was off. I replaced the driver side regulator/motor with a good used setup. Replaced the tranny and diff fluid. Still have three issues to address before I can get it inspected in WV.

1. Brakes are hard as hell to push and the brake light is on in the info center. I suspect the booster.
2. Wiper motor linkage has fallen off. I need to get a new snap plug (not sure of proper name.
3. This one has me asking for help. The trucks turn signals and 4ways do not work. I checked the bulbs, fuses, and swapped the flashers with known good. No change. Checking the schematic the two circuits do not share a fuse. The only thing I see that they share is the turn signal/wiper/flasher switch. This will be my next step, the manual has steps to check the switch. I have a new one, I thought I would take the covers off and plug into the new switch tomorrow.

Has anyone else had the flashers and turn signals go out at the same time? What was the issue? Thank you

Robert

 

1. Could also be vacuum pump or plumbing
3. Multi function switch is the likely culprit

 

I hope the vacuum pump is not the issue. I never have had one fail. Not in close to a dozen trucks. Doesn't mean they cant! I thought the vacuum pressure switch would cause a check engine light though? The oil weal doesn't leak or nothing, I would hate to replace it to as they are kinda pricey

I hope the multi switch is the issue. It really is a clean truck aside from all the small issues. The motor purrs like a kitten. It will be the only 2wd diesel we have ever owned.

 

Sounds like you bought it right though.
I am assuming you guys picked it up at the Carlisle show.

Sorry we didn't run into each other, I didn't see the red 12v Ramcharger this year.

 

Oliver I actually found it on Craigslist for sale down near Washington DC in Annandale VA. I was parked in my normal spot at Carlisle (in the grass lot outside the restaurant parking lot). I was there from 8am til roughly 3pm or so on Fri. I also had a small flatbed trailer hooked up behind it to haul a set of AMD 1/4's home for my Barracuda.

 

Ok, today I started trouble shooting with a 92 manual since I didn't have a 91. It took me all of 20 min to find a fuseable link was bad. I cut it out and installed a fuse link with a 20amp fuse. I then turned my attention to the brakes. I pulled a booster from a donor and installed it on the 91. The hard peddle didn't go away. Is there an easy way to test the vacuum pump to see if its producing enough vacuum? I have never had a vacuum pump fail. If I had brake issues it was always the booster, master, or a leaking wheel cylinder. When the pump fails what exactly fails inside it? Is it one of the diaphrams on the side or bottom? Thank you to everyone for the helpful advice

 

You pull the hose off of it, put your thumb over the hole, and see if it ****** vacuums.

Actually, the vacuum pump isn't a high flow unit by any means. If the vacuum hose connector is off the heater control, it'll dump enough so nothing works.

The vacuum sense switch under the hood near the driver's side hinge, and is wired in parallel to the switch on the park brake. Turns on the brake light, and from that the ABS control if you have one will turn on the ABS lamp.

 

With a failing to failed vacuum pump your brakes will loose from some to all power assist.
Pucker factor-10.

Your truck will still stop, but you will need both feet in a panic situation.

https://www.dieseltruckresource.com/...d.php?t=165546

Also when checking the vacuum diaphragms check them seperatly, they are connected in parallel through a wye and the bad unit will bleed down the good unit leaving insufficient vacuum for the booster.

 

J Martin/ Mr. Lane if it is a low vacuum issue wouldn't the abs/brakes light stay on? The previous owner did inform me when we were loading it that it had been like this for some time and that since he only used the truck less than a handful of times a year he never bothered to mess with it. But like all the little things I have been fixing, some mentioned. It would have bugged me till it was fixed. The truck spent the last several years in VA. How he ran it without wipers, turn signals, and half the running lights out is beyond me. In WV I would be pulled over within the first hr of it being on the road. Easy ticket money for them Hell, I have to get it inspected to drive it.

 

The low vacuum switch turns on the brake light. When the brake light is seen by the ABS, it is supposed to turn on the ABS light.

Would a multiple fault surprise you?

The other possibility is that the vacuum sensor is broken or disconnected, and something else, like the balance switch is setting the brake light.

Vacuum sucks. It should be pretty easy to check it out, even without a gauge. It's a lead pipe cinch to verify it with a gauge.