My Fuse for the ECM keeps popping.. not sure why.. have looked for lose or broken connections.. but could not find any yet. It happened on a long drive back from Reno (3hrs).. while on the Freeway and came to a interchange doing about 75mph.. went into the turn about 65 and keep it there as I came out of the turn, the CEL came on..! I have swapped ECM, Prom's. opened up some of the wiring harness around the ECM connector looking for shorts, etc.. checked the engine compartment for the grounds and shorts.... any suggestion or problem that are simular that you had found something ?

The ECM fuse supplies power to a number of sensors in the engine compartment. I suggest you visit this link and look at Fig. 15. You will need to trace all the PNK/BK wires from the ECM fuse to find the short. Although this circuit ends up at the ECM, main power to the ECM is via a fusible link connection. The fusible link is located in the engine compartment.

Note that there are also circuits fed from another fuse that are also colored PNK/BK, so you will need to pay attention when you are tracing the circuits.

http://www.autozone.com/az/cds/en_us...rInfoPages.htm


Dave

Dave

Thanks for the info..

I know the Fusible link is still good.. The fuse that keeps popping is the one at the interior fuse box.. That being the Pink/Black one. I will continue to trace out some of the wires..

Question, what do you think.. if the wire from the fuse box is good and still popping fuses.. there must be some short of loose connection o the other side of the ECM to be causing the fuse to blow. But what circuit or ground would cause that condition ?

thanks..

If you are continuing to blow the fuse, you have a short to ground in one of the PNK/BK circuits. The short could be anywhere in the circuit from the fuse box to the ECM and into the engine compartment.

You might try this...Pull the ECM fuse, Disconnect the ECM connectors and then disconnect C207 which is the connector under the dash just to the left of the ECM.

Now take an ohmmeter and ground one side and connect the other side to the PNK/BK wire in the C207 connector, first to one side of the connector, then the other side of the connector. Then you will need to continue tracing the PNK/BK wire on the side of the connector that gives a short to ground reading (0 ohms).

I would concentrate on the wiring to the sensors in the engine compartment if you get an indication of a short on that side of Connector C207.

In the 82 Service manual wiring diagrams the circuit is routed like this...

It starts at the fuse box ECM fuse with a PNK/BK wire which is routed in the I/P harness to Connector C207 on the pass. side of the dash, then it goes to the engine compartment with the other ECM wires in a harness that connects to a connector by the passenger side kick panel, thru the body and up into the engine compartment just behind the right front wheel well, below the blower motor. Then the PNK/BK wire is spliced (I assume the splice is inside the harness "near the blower motor" in the engine compartment). One PNK/BK wire returns from the splice to the ECM connector and provides 12V to one point on the ECM. All the other wires from the splice go to various sensors in the engine compartment. Which sensors depends on the engine type V6 or V8 and if it has a carb or is fuel injected. You will have to identify all the sensors in your model year that are connected to that circuit and check the wiring to each one carefully.

Have you removed any sensors and cut the wires to it? A bare wire end to the block or valve covers = short and blown fuse. You could have a cracked or bad connector at one of the sensors which is creating a ground. You could also have a wire run that has a small portion of the insulation melted or scraped off and the copper is touching metal at that point.

The bad part about tracing this circuit in the engine compartment is the splice point. All of the sensor circuits are common at this point, making it hard to isolate the wire that may be grounded.

So you will just have to spend the time and inspect and verify each circuit. One thing you can try is to take the splice apart, disconnect all the sensors and test each PNK/BK wire from the splice point to ground with the ohm meter. That may identify the wire that is shorted. I don't know how much is required to take the splice apart or put it back together again.

Isn't tracing wires fun

Dave

i having the same problem in my truck....its also a tbi...ive checked all sorts of wires but cant seem to find the problem.....let me know if you find the problem

Anyone know what sensor is in the passenger side head.. it's not the knock sensor, it is above it in the head between cyl #8 & #6. Single green wire?

I know the coolant sensor is up top on the manifold.. or is this a second temp sensor ?

thanks..

figured it out.. it was the Coolant Fan Switch..

I figured it out.. it was the Coolant Fan Switch and wire, I have replaced both the switch and the pigtail. Will have to wait and see if this fixes the ECM/Fuse problem.

Had a problem, while jacking up the car, It slipped off and the car fell on the jack and bented the crosslink and pushed it up into the Oil Pan and bent the pan enough so that the crank/rods now hit the pan. I will have to change the oil pan out...! what a mistake that was..!

wow i am having the same problem. i put in a 30amp fuse and it blows it right away. waht gives. grrr..times like this i like carb set ups. i look at all that wiring and i get the impression i am looking at a bowl of spaghettis. my car has the digital dash and it has more wires than a 747. i changed the ecm followed wires and nothing, i will look at the temp. switch maybe thats the problem. i hope so!!

Ikeepitreelz... Not sure if I resolved the problem, as I was only able to start up the engine for a second or two. due to the oil pan being dented. But it didn't throw any codes, as before it would throw one right away. But I will have to wait until it is running for more than a few seconds.. should be in the next week or two (need to fix trans now).

Any of the switches that go bad can cause problems with the electrical system... intermittent shorting or spikes due to a bad sensor or switch.

This is the second sensor/switch that has cause me problems. the 1st time a few years ago was the Temp sensor on the top of the intake. It had looked ok, but after pulling the connector off, it was all messed up inside the sensor and connetor. Replacing both resolved the problem that time also.

So I am hoping that once I get it all back together.. that Fan Switch will be the cause of my current problem.

follow up: Guess what i decided to by pass the fuse so i bridged the connector and of course it made a bad spark, i did it again and nothing i was like oh boy i must of fried something but its weird NOW my fuel pump and ecm WORK!!! what the hell? my car runs, now i got a different problem my dash is digital and now it only display kilometers per hour. i think that fuse also controlled maybe the vss and i fried something... anyone have any clue? i saw this guy the other day that carburated his car he removed the harness that controlled switches sensors and all, he left the basics and he went carburated at the time i was like wow he is dumb!!..lol i think i am the dumb one now lol. oh yes and you know the problem with the fan switch is that its so close to the exhaust mines was off hanging out but that wasn't the problem. i rather change a motor in 14 degree weather(which i did this winter) than pin point an electrical problem..

Try disconnecting the battery for about two minutes then reconnecting it to see if the dash resets.

hmmm.. will try that..but i think i fried a wire stupid me...

Well.. It is now running again.. No codes being store (for now..).. I guess it was the Fan Temp Sender that was shorting out or something.. the connector and sensor was in bad shape. It looked and felled like the heat had gotten to it. The connector broke apart on removing it and the metal connector inside it and the sensor was not in good shape..

So, you guys that are trying to figure out the same type of problem.. this is the second sensor that has caused me chronic problems.. the other was the Water Temp sensor.
My suggest is to check each and every sensor, get a scanner that can monitor each sensor... disconnect and check the inners of the connector and sensor. Replace any sensor and pigtail if they even look bad. I hope my adventures will help some find there problem.