Went out to start my 2001 RWD BLAZER and car kind of "jumped/lurched" but then wouldn't start. On 2nd start attempt, There was no power, no dash lights, no ignition activity...nothing. I waited a couple of minutes and the blazer started. I then drove the blazer about 10 miles where it sat for 3 hours. I then started it with no problem but while driving back home I was at a stoplight after getting off the interstate and and it died. No power again, no dash lights, just like before. I waited a few minutes and the car started and I drove home with no issues. I have since driven it only around the neighborhood for the last two weeks with no electrical issues but reluctant to drive any further. A friend told me that it might be a resettable relay in the fuse box... If so, any ideas on which fuse should be replaced, or how to check the resettable fuses? Any other ideas on the source of the problem would be appreciated.

FYI, Battery and alternator were replaced about a year and 1/2 ago.

 

When it won't start does it crank?

What do you mean by no ignition activity? Did you check for spark or do you mean no 12V power to the ICM or coil?

"Jump/lurched", meaning that it acted as if it was in gear and tried to move forward during cranking?

Check all your cables and connections at the battery and alternator for loose or corroded connections.

This may be the ignition switch since the dash goes dead but there are other possibilities. You will need to travel with a volt meter to find the problem. The next time this happens check the input voltage to the following fuses and see if any of them have lost their ignition switch voltage:

ECM1, 15A UHFB - ignition
Gauges fuse 4, 10A IPFB - dash gauges
Clstr fuse, 10A IPFB - dash cluster

And if no power there check the voltage out of the IGN A fuse, 40A in the UHFB

None of these functions use the retained pwr relay.

Apparently a heavy key ring can kill the ignition switch.


George

 

Thank You for the response. In answer to the questions:
> It does not crank when it won't start. There is no cranking, ticking sound, just silence.
> It was not in gear.

Thanks for the tips! I will check all cables and connections. And also the fuses that you mentioned. I have been driving the Blazer for about two weeks since this happened but staying close to home and no problems.

 

THe fact that is does not crank does complicate things but because the dash lights go dead it still implicates the ignition switch so I would stick with the original testing. Just leave it in the run position when it won’t start and test. If that looks good then we can move on to the starter circuit.


George

 

I am unaware of any "resettable" fuses in your truck. There is one circuit breaker in the body relay block which is presumably resettable but it is for the power seats.


George

 

Oddly enough I had a very similar problem this morning. I have a 98 Blazer and I was driving the highway to work and effectively I lost electrical for a moment shutting the engine off at 60mph. Thankfully I was able to pull over safely. The vehicle immediately started back up once I should get it in park and turn the ignition.
Continued the drive and the engine "staggered" (kind of lurch as the engine kicked back in) a few times but didn't fully shut off. Battery warning light flashed on in those times. It's currently sitting in the parking lot and I'm hoping it starts for me to get home.

 

When you have a new problem you should start your own thread otherwise we wind up with two parallel discussions that get confusing.

What do you mean by “lost electrical”?

This could be fuel pressure, ignition or fuel injection.

When it won’t run/start you should measure your fuel pressure after key on and if it will crank do you have spark? Those first two are pretty easy to check, fuel injection is more involved but also the least likely.



George

 

it sounds like the battery or a connection is not up to par, if the battery has one or multiple dead cells and just cant deliver the amperage it will just not bring power to anything if it has a sustained amperage draw higher then it can maintain. alternatively if the positive or negative terminals are not making good connection you will loose power almost like a fuse blew. twist and tighten the bolt on the battery cables and get the battery tested, next step is to look for any loose direct connections to the battery that would short out on the positive lead, or bad/missing ground straps.