1991 Chevrolet C1500 - Page 2 - Answered Questions & Fixed issues

You have a bad heater core ! http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0CCUQtwIwAQ&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DeVe_VU9ORS8&ei=jpnRVKzGK4inggS_l4LgAg&usg=AFQjCNEBZrBlTVSFzQTlC9B5CdPy_GrZZA&sig2=PKzzFgt2yXBwcSYhGwr-ww&bvm=bv.85076809,d.eXY

Under the dash board there is an electrical block with nothing plugged into it. there are 2 rows of terminals. on the top row on the right is terminal "a". terminal "b" is the second one in from the right. terminal diagram labeling is like this from left to right.
top row,"F", "E", "blank","C","B","A"
bottom row "G","H", "blank","blank","blank","blank"
take a small piece of wire and jump terminal "A" and "B". i found an unfolded paper clip works well. with the terminals jumped, turn the key to the on position.(DO NOT START ENGINE) with the key on, the service engine light will start flashing codes. count the flashes. it will repeat each code 3 times before moving on to the next code. your first and last code will be a code 12. that is just the test code. it lets you know you did it right. you will see 1 flash with a short pause then 2 flashes. after you see that 3 times, your next code will be your trouble codes. when you see code "12" again, there are no more. if you tell me what the codes are, i'll tell you what the mean. hope this helps.

Look for a burned fuse link in the wiring harness

Have you confirmed whether the engine is actually over heating or is it just a bad temp sensor?

The slave cylinder on the transmission is leaking. It may be rebuilt or replaced. It will have to have the air bled out of it either way you go. The bleeder screw in on the side if the slave cylinder .

Did you check the underhood sticker? Usually tells you what steps you need to perform. On your truck it might be automatic, you would beed to set the initial timing and then the computer sets the timing after that.

The only thing that will keep it from starting, since you have fuel and spark at the plugs. Would be really low compression. Under 90 pounds on most of the cylinders.

This is an internet form or chat room You ask those questions at repair shops, when you go for an estimate-- AFTER-- you pay them to diagnose & find a problem Why not do the work yourself !

best advice is to have a turbo fitted by an accredited turbo specialist shop. They will have the equipment, knowledge and chips available to tune the engine on a dyno to pass regulations. They will also be certified to fit the modification plate to the vehicle to keep you legal.

find out witch door sensor is grounded out and dome will go out

what lights. the FSM covers them all, name a light. just one and we can post 1 page of the 100.

Need a little more info on your truck....I'll give this answer a try. Do you by chance have a 4.3L, 5.0L or 5.7L vortec engine in your 91. If so and it is overheating immediaetly after start up sounds like you have cylinder head gasket or head problem. The vortec engines are prone to this if they run to hot. I’m happy to assist further over the phone at https://www.6ya.com/expert/randall_d932ef6e01588b0f

sounds like your pitman arm is wore out

Spunds like your pitman arm is worn out.

The brake light assy is spring loaded and sounds like it should be replaced. If the pedal travel is too low indicateing low brake shoes, this may also need replacement.

your cluster panle has probleems

Poor reception is ant. No reception is radio. Poor explanation gets poor answer

it could be that the fuel isn't getting to the engine when your accelerating. try checking to see if the fuel filter is clogged, then try checking all of the filters

Check engine light on? Does it run normal driving it? Sounds like a vacuum leak. Check the gasket under the throttle body.

There is a vacuum controlled actuator under the dash that opens a door exposing the heater core to the vent system. Sounds like the door isn't opening. Check your vacuum lines under the dash..