I have a 1987 K5 350 TBI, 700R4 blazer. When I turn the key I get a click then no power anywhere in the vehicle except the rear electric window. When I disconnect and reconnect the battery cable the door locks try and auto lock. I have no lights, gauges, starter and its a new battery that is good. Any thoughts?
CK5
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Electrical issues
- Thread starter K5-CJ5
- Start date
I will look at my schematics, but unless its a blown fusible link, I suspect I've got bad news for you.
The door locks trying to autolock sound like someone has put an alarm system in the vehicle and its tripped.
This can be a major PITA. You never know what has been modified or how.
However, its possible that the lock button is stuck on the door, and you have a normal electrical problem.
If so, then odds are the battery is dead. Sounds like the door locks ran the battery down. Does the window move at normal speed?
The door locks trying to autolock sound like someone has put an alarm system in the vehicle and its tripped.
This can be a major PITA. You never know what has been modified or how.
However, its possible that the lock button is stuck on the door, and you have a normal electrical problem.
If so, then odds are the battery is dead. Sounds like the door locks ran the battery down. Does the window move at normal speed?
I haven been working through the wiring and have found that there are two (I think relays) connected in-line with the door locks and lock switches have been removed from the doors completely. I put a new battery in and haven't left it connected because I thought the auto lockls would draw power. I can turn ignition to on an get a reading on the volt gauge but as soon as I try and start there is a click and I loose power everywhere. I have pulled the started and crossing using cables have determined it is working. There are 2 orange wires at the starter 1 is connected to the "s" terminal the other is a bare handing wire. Is the second wire supposed to be connected to the "s" terminal as well (These are in addition to the POS cable from battery).
The door locks seem to be connected so that when 1 lock (drivers) is locked/unlocked the other (passenger) follows suit. I have also found a Black wire coming down from the steering column that has a end on it similar to a circuit board chip and I don't see where that would plug into.
The door locks seem to be connected so that when 1 lock (drivers) is locked/unlocked the other (passenger) follows suit. I have also found a Black wire coming down from the steering column that has a end on it similar to a circuit board chip and I don't see where that would plug into.
I've got to run, I'll be back online later. In the meantime, lets assume for now that it is not an alarm issue.
The power for the whole truck obviously comes from the battery. It gets there down the main positive cable to the starter.
And, of course returns through the ground.
At the starter, where the main cable hooks up, there should be two red wires that are either fusible links, or hook to fusible links.
A bad ground cable or connection, bad main positive cable, or bad fusible link or connection would give the same symptoms you are seeing.
When you measure the voltage under no load, you have power.
As soon as you put the load to it, the bad connection will not let that much power flow though it and the voltage goes away.
You find this by finding the voltage drop.
Turn on the headlights to put a load on the system. If they come on, stop and go back. They should not come on.
Put the positive probe of your voltmeter on the actual battery terminal, not the clamp.
Put the negative one on the terminal at the starter if you can.
If the wire and connections are good, you should read 0 volts.
Do the same with the negative post, with the other probe going to the frame, but reverse the polarity. ( Put the negative probe on the battery)
Keep following the power that way until you find 12 volts. The problem will be between the two probes.
( Go from the starter post to where the red wires hook up.)
The power for the whole truck obviously comes from the battery. It gets there down the main positive cable to the starter.
And, of course returns through the ground.
At the starter, where the main cable hooks up, there should be two red wires that are either fusible links, or hook to fusible links.
A bad ground cable or connection, bad main positive cable, or bad fusible link or connection would give the same symptoms you are seeing.
When you measure the voltage under no load, you have power.
As soon as you put the load to it, the bad connection will not let that much power flow though it and the voltage goes away.
You find this by finding the voltage drop.
Turn on the headlights to put a load on the system. If they come on, stop and go back. They should not come on.
Put the positive probe of your voltmeter on the actual battery terminal, not the clamp.
Put the negative one on the terminal at the starter if you can.
If the wire and connections are good, you should read 0 volts.
Do the same with the negative post, with the other probe going to the frame, but reverse the polarity. ( Put the negative probe on the battery)
Keep following the power that way until you find 12 volts. The problem will be between the two probes.
( Go from the starter post to where the red wires hook up.)
Thanks for your help! I just picked up the Blazer yesterday and thought it just needed a battery and starter. Didn't need either! Nice after-market alarm installed behind glove-box and tied into all kinds of circuits. I was able to disconnect from all the circuits and remove, Blazer fired right up and ran perfect!
I am still curious if anyone has seen the power locks run off the tumblers, no switches in door, and connected together so if one locks/unlocks both activate. Its def. not stock and I haven't seen it in my other blazers. Any thoughts?
I am still curious if anyone has seen the power locks run off the tumblers, no switches in door, and connected together so if one locks/unlocks both activate. Its def. not stock and I haven't seen it in my other blazers. Any thoughts?
All right! Glad you got it going. Some of those aftermarket alarms can be a real pain. Not just in their operation, but in their removal.
Some of them cut so many circuits that its takes forever to get everything tied back together.
The door lock thing sounds like more of the same alarm stuff.
Some of them cut so many circuits that its takes forever to get everything tied back together.
The door lock thing sounds like more of the same alarm stuff.
The door locking circuits were not toed into the alarm system at all. In fact this Blazer has Power windows but there are no lock switches next to the widows switches like I have on my other Blazers. Were there any packages that just dint have power locks(factory) even with power windows?
I found a Bitron Video Control relay for the door locks under the dash, part #2043002. I searched and found that it is an auto door locking system from Italy that was used on Masserati's! It seems to be wired independently of all circuits and only effects the auto door locks. Has anyone ever heard of these in a Blazer?
I am able to start the Blazer now and have full electrical power since the removal of the alarm. Occasionally I try and start and it trips the electrical system and in order to reset I have to disconnect the battery and reconnect. Sometimes I have to do this multiple times before it will engage and start. Is this a fault in the starter or should I be looking into other wiring issues?
I also found 2 40amp circuit breakers wired in line to the power windows. I don think it was factory but I could be wring. Im beginning to think the blazer didnt have power windows or locks form the factory and were added after market.
I am able to start the Blazer now and have full electrical power since the removal of the alarm. Occasionally I try and start and it trips the electrical system and in order to reset I have to disconnect the battery and reconnect. Sometimes I have to do this multiple times before it will engage and start. Is this a fault in the starter or should I be looking into other wiring issues?
I also found 2 40amp circuit breakers wired in line to the power windows. I don think it was factory but I could be wring. Im beginning to think the blazer didnt have power windows or locks form the factory and were added after market.
Don't think they ever put anything like that in a Blazer. That whole setup sounds like Previous Owner stuff.
If you removed all the alarm stuff, there should be nothing there to trip. When it trips, does it kill all the electrical, or just the starter?
Normally I would say you have a starter solenoid or ignition switch problem, but in your case, it could still be part of the alarm system.
Most of those systems have a starter kill circuit to keep it from cranking, and a circuit or two to kill the ignition and or fuel if you have an electric fuel pump.
Back in the old days before fuel injection and electric fuel pumps, they had little solenoid valves in the fuel lines to cut the fuel off when the alarm tripped.
If yours has the starter kill circuit, it might be causing the problem, but there would have to be a brain of some kind to trip it, since it works sometime and not sometime.
Otherwise, it would just be on or off all the time.
What does it do when it doesn't crank? Does it click when you turn the key, or not?
If you removed all the alarm stuff, there should be nothing there to trip. When it trips, does it kill all the electrical, or just the starter?
Normally I would say you have a starter solenoid or ignition switch problem, but in your case, it could still be part of the alarm system.
Most of those systems have a starter kill circuit to keep it from cranking, and a circuit or two to kill the ignition and or fuel if you have an electric fuel pump.
Back in the old days before fuel injection and electric fuel pumps, they had little solenoid valves in the fuel lines to cut the fuel off when the alarm tripped.
If yours has the starter kill circuit, it might be causing the problem, but there would have to be a brain of some kind to trip it, since it works sometime and not sometime.
Otherwise, it would just be on or off all the time.
What does it do when it doesn't crank? Does it click when you turn the key, or not?
The starter will click and then I loose all electrical until I remove battery cable and replace it. It doesn't happen all the time only occasionally. I have started it multiple times in a row with perfect results and then I have tried and it will do it a couple times then start. I just went out again after letting it sit awhile and again it worked perfect.
I would crawl under, and carefully inspect the connection where the big battery cable hooks to the solenoid.
I suspect that you have a loose connection there. That is where the entire vehicle gets its power, and that connection get jarred every-time the starter solenoid fires.
And it also gets wiggled slightly when you remove the battery cable from the battery.
I would disconnect the battery cable at the battery, then take the big cable and the two red wires loose at the starter and clean the connection and put it back on.
Odds are that will cure the problem.
I suspect that you have a loose connection there. That is where the entire vehicle gets its power, and that connection get jarred every-time the starter solenoid fires.
And it also gets wiggled slightly when you remove the battery cable from the battery.
I would disconnect the battery cable at the battery, then take the big cable and the two red wires loose at the starter and clean the connection and put it back on.
Odds are that will cure the problem.
