New to 5.3ls... need help getting it started
12 Second Club
Joined: Jan 2014
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From: 217
Since you have a good crank sensor and a known good PCM.
1)verify harness is pinned correctly
2) Check continuity between crank sensor plug and PCM connector terminals.
3) check continuity between pcm and coil connectors terminals
4)check harness from coil connector terminals to each individual coil terminals.
5)If harness fails find issue and repair or send back
6) If harness passes, verify input from crank sensor to PCM and PCM coil output to coils.
We are assuming all pink wires are keyed hot in crank and run.
1)verify harness is pinned correctly
2) Check continuity between crank sensor plug and PCM connector terminals.
3) check continuity between pcm and coil connectors terminals
4)check harness from coil connector terminals to each individual coil terminals.
5)If harness fails find issue and repair or send back
6) If harness passes, verify input from crank sensor to PCM and PCM coil output to coils.
We are assuming all pink wires are keyed hot in crank and run.
Launching!
Joined: Feb 2010
Posts: 276
Likes: 1
From: Mid Mo via Lancs. England
If the cam sensor wiring checks out, and ohming it checks out, try to run the PCM hot wire directly to the battery. I had a SBC swap in a Jeep years ago that would not fire. Turned out that the PCM was losing voltage when the engine cranked and wouldn't fire the coil. After running straight to the battery, it running fine, I wired to the battery and had no issues.
I had another one where the customer bought a Painless harness. Turned out they (Painless) had a bad connection on a live wire where it branched out. Redid the connection and all was well.
Since then I have used a direct feed to the PCM for the permanent live, with a fuse of course.
I have found pinouts in various places, and just Googling "2001 Chevy Tahoe PCM pinout" etc normally brings them up
Martin
I had another one where the customer bought a Painless harness. Turned out they (Painless) had a bad connection on a live wire where it branched out. Redid the connection and all was well.
Since then I have used a direct feed to the PCM for the permanent live, with a fuse of course.
I have found pinouts in various places, and just Googling "2001 Chevy Tahoe PCM pinout" etc normally brings them up
Martin
Thread Starter
Teching In
Joined: Aug 2014
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Well so far no good. I have followed the above mentioned steps 1 - 4 and everything checks out just fine. I do not completely understand step 6, need some input there. Also someone mentioned checking cam sensor wiring and ohming it as well. Not sure what to do there. Still no spark.
12 Second Club
Joined: Jan 2014
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From: 217
Each time the crank sensor sends a voltage signal to the pcm, The pcm see crank position, then calculates which coil to fire. The pcm will complete the circuit to the coil to energize the coil, when the circuit becomes open again the coil fires. Electricity always wants to go to ground and the spark plug electrode is the only available one then you have spark(provided no broken wires, cracked spark plug, or bad plug wire). Since pink wires are hot in run and crank, that means the signal wire is the ground for coil that opens. Its no different than old school distributor other than you added a crank sensor and computer in place of distributor.
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12 Second Club
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From: 217
TECH Regular
Joined: Sep 2007
Posts: 443
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From: Kansas City, MO
Did you change the camshaft. Gen4 cams don't have the tone notches on the back. And you're sure you have the pcm orange wires connected to a constant hot? Also the pink wires need b+ in crank and run. Is there a ign relay? Does it stay energized when cranking?
Also make sure you have about 58-60 psi of fuel pressure.
Also make sure you have about 58-60 psi of fuel pressure.
Thread Starter
Teching In
Joined: Aug 2014
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OK...working backwards on the last list of questions.
Fuel pressure is spot on.
I am using an ignition relay, and it stays energized while cranking.
Yes on the pink and orange wires.
I did not change the cam shaft...all stock except for headers.
So tell me more about gen 4 engines not having tone notches...if that is the case, then why is there a cam sensor behind the intake manifold? Or is it a cam sensor at all. What ever it is, it did not give me the same readings as the crank position sensor that is located behind the starter.
Sorry if I am rambling. I did send the PCM and wiring harness back today to have the two units checked by the experts at Novak. Sure hope the find something.
Fuel pressure is spot on.
I am using an ignition relay, and it stays energized while cranking.
Yes on the pink and orange wires.
I did not change the cam shaft...all stock except for headers.
So tell me more about gen 4 engines not having tone notches...if that is the case, then why is there a cam sensor behind the intake manifold? Or is it a cam sensor at all. What ever it is, it did not give me the same readings as the crank position sensor that is located behind the starter.
Sorry if I am rambling. I did send the PCM and wiring harness back today to have the two units checked by the experts at Novak. Sure hope the find something.
A 2004 is a Gen3, and that is a cam sensor at the back of the engine, but im pretttsure it would start even if it weren't hooked up as long as the crank sensor is hooked up. If you were seeing RPM on the scanner while cranking, and everything is staying powered during cranking, then im going to guess its a wiring harness issue. If you have power to the coils then it almost has to be a ground problem. Could be a PCM problem, but I just dont think thats as likely.
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Teching In
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Finally got it started...
Sent the wiring harness back to the folks at novak and found a break on one of the ground wires. Life got in the way though and I was just able to plug everything back in. Fired right up and runs like a champ. Sounds beefy too.
Trying to keep the original Jeep inst cluster... any thoughts on an engine temp sensor adaptor from the metric 5.3 port to the standard amc port???
Sent the wiring harness back to the folks at novak and found a break on one of the ground wires. Life got in the way though and I was just able to plug everything back in. Fired right up and runs like a champ. Sounds beefy too.
Trying to keep the original Jeep inst cluster... any thoughts on an engine temp sensor adaptor from the metric 5.3 port to the standard amc port???
