20 Most Recent 1985 GMC K1500 - Page 8 Questions & Answers

Hi and welcome to FixYa!

Only one left to check out. The brake switch, it is located underneath the brake pedal. If the switch is faulty it won't trigger the brake lights. Once replaced you'll be good.

Hope this helps and thank you for using FixYa! Have a good one!

DTC 42 is the code for an open circuit in the power control.I would strongly recommend that you have your PCM tested for shorts.It could be a grounded circuit Or bypass circuit.My best advise would be to get your Power Control Module tested.

What year, make and model do you have? You are looking for the IAT to hook up a performance chip?

If you have a Pep Boys in your area they'll be happy to provide a no obligation estimate for this.

When there is an engine misfire it could be gas or spark related. Or, the oxygen sensor may not be operating correctly, which controls fuel supply.

If there is a 'random misfire' then it could be an oxygen sensor causing the problem, as well, causing a rich mixture.

Good luck on this repair.

Sounds like carburetor issues. Check your accelerator pump. Do you get a good stream when you throw the throttle open? On the stalling issue, the carb should have a dashpot that keeps the throttle from slamming shut.

The V.I.N. won`t help unless you`re a G.M. dealer. Z71 is a type of R.P.O. code or package for a particular truck. Go to your glove box or center console, there is a SPID label, indicating all the R.P.O. codes for your vehicle. Its in alphabetical order, just follow thru to Z71. If it is it`ll be there. If not it didn`t come with that package.

White, thick liquid on your oil dipstick is an indicator of engine coolant leaking into your crankcase. It's a major problem that will cause your engine to be destroyed eventually, if you don't have it fixed asap.

if it was me i would stop by my local library and see if i could get my hands on a Haynes auto repair manual for my truck or stop by your local GM dealership in the parts department and see if they can help you wish you the best of luck Michigan Man.

Looks like a bad MAP sensor to me.

the alternator will not die in one day unless there is a direct short causing diode or coil winding failure which would give signs of smell, melted wires. Disconnect battery and give full charge. what year is this? while vehicle is running you should be able to briefly disconnect positive battery post connection and vehicle will still run if alternator is good. For a new battery to die in one day, one of two things i think has happened. Either the batt is faulty from supplier,( not likely but i have seen it ) or there is a direct draw or grounding taking place whether its direct in the starter selonoid or a direct draw through accessories. Are you sure all switches are off ? Push switches (on interior lights) nothing like dome lights,delayed lights are staying on! Does vehicle start hard like it almost needs a jump. If it has to be (and it takes time). to find out what is drawing the power ( i am old school) disconnect positive power source on batt. 2) disconnect ignition power source on starter. 3) connect pos batt wire to starter, 4) touch positive cable to positive batt post and look for spark or contact. if this reacts then selonoid or starter motor is shorted drawing the current. Or if you have volt meter and know how to use it, this is good to. If checks good then hook ignition connection back on starter.(disconnect pos terminal on batt prior to re-connect) I think the battery is having the life sucked out of it by a short in the system ( A DRAW ) this could be a quick find or fix or this could take days to track down. alot of variables here to try to explain. but i would seek into the starter first as usually this drains the battery quickly .

Bad connection at battery or block ground.

Hi, the front axle has a sensor, that tells you with a light, that you are in 4wd. If the front axle actuator does not engage the axle, the light will not come on.The actuator is most likely at fault. If you remove the actuator, and press the button inside in, you may be able to engage the axle manually, and with the key on, see the light. I would consider checking to see if there is power, and ground ,key on, at the actuator. If there is, than you have an actuator, or internal axle issue. Good luck... Coop

Your problem, as to my knowledge, seems to be more of a ground issue, or power supply issue. Check the grounds throughout your vehicle, including the ground for the fuel pump.

Hi, you may have a torn fuel pressure regulator diaphram. The diaphram is behind a square cover on the side of the throttle body, that is held in by 4 screws. Take the diaphram out and check it for tears. If no tears, put it back the way you took it out and check your injectors. Can you see them squirting as you pull the throttle? Is the squirt the same for both? Is it a regular pattern or distorted? If you see issues there, you can take them out and try to clean them. If that doesn't work, replace an injector that has a poor or irregular flow pattern. Please let me know if you have any questions, and thanks for using FixYa.

P0420....Catalyst System Efficiency Below Threshold (Bank 1),i would be inclined to check the O2 sensors ,the two wires the same colour which is normally white should read 12v across them ,with connector off then these two wires should measure a resistance ,the other check requires a scope to read them but it should show 5 volts over a time scale on the scope with time scale decreasing with higher RPM ,but as this vehicle is 13 yrs old then i would be inclined to suspect the cat as breaking down inside and depending on mileage due for renewal as they dont last forever ,small exhaust and if smells a bit off or stinking of rotten eggs then renew the cat and the sensors ,Cats are good for around 150,000 then after that they start to clog up and the porcelane base break up .

Not too good. The least expensive change you can make is the oil. Go to a Mr Lube and have them do a hot change and put an additive into it. The new oil will help the clutches to grab and the additiv e will free up the valve body to shift properly. If that doesn't work you either need to rebuild it or replace it with a used one. Sometimes you can get lucky and find factory GM rebuild at the wrecker that will give you years of good use. The key is fresh oil and change it after the first 20k, then it's probably good for 60 more.