Get it started and have the shop do the relearn at same time.
Help! 1999 Chevy Tahoe no start issue!
- Thread starter Sammie859
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
iamdub
Full Access Member
It's when you put the ECM into a programming mode to make it learn the signal from the new crankshaft position sensor. No, it won't keep it from starting as the engine has to be running as well as held at 3000 RPM (I think) to complete the learning process. I was just mentioning it in case it wasn't performed. It'll probably run fine without it, but it'll never be quite optimal. Any decent shop worth their business license should know to do this and include it as part of the CKP sensor replacement. You need special equipment to put the ECM into the programming mode, so it's a mechanic shop job. The shop that replaced the sensor owes you this if they didn't do it. It only takes about a minute.
YukonGTmaster
Full Access Member
- Joined
- Mar 18, 2021
- Posts
- 526
- Reaction score
- 994
I’m sorry you are having such a hard time with this. You said you had the spark plugs and wires replaced. This is a shot in the dark, but…. See if the plug wire for #5 and #7 cylinder are plugged onto the wrong spark plug. It is “Very” easy to install these wrong. There should be numbers at the distributor cap. #7 wire has to go furthest spark plug back to the firewall on drivers side. #5 has to go just forward of that plug drivers side. I usually have to touch the wire and keep touching it as I follow it from the distributor to the plug. Don’t give up!
Attachments
Last edited:
iamdub
Full Access Member
So, the order of events is:
1) The check engine light came on, so you had the injectors replaced (did you ever read the code(s) then or you did you go straight to replacing the injectors?)
2) When you got it back, the light was still on, so you went to find what the code was and found that it was for a crankshaft position sensor
3) You replaced the crankshaft position sensor, spark plugs and wires
4) Engine wouldn't start after that
Did you get the CKP sensor from AutoZone and is it their house brand? Do you still have your original CKP sensor?
iamdub
Full Access Member
So now it's a camshaft position sensor code? What happened with the crankshaft position code and sensor replacement ordeal?
Sounds like a security issue to me if the security system kicks in it prevents the motor from getting spark .I would try to do a reset which is basically turning the ignition over to acc on then back off 5 times
OP
OP
Sammie859
Member
Yes this is the order of events except your #1 I had injectors replaced because I was having issues with it randomly not wanting to start-thought it was fuel pump but shop diagnosed it as 2 bad fuel injectors. ThTs why I had those changed. Then when I got it back. It had the code for the camshaft sensor. So I was going to change that and the crankshaft sensor. (Crankshaft got changed first) because it was broken off. (Never changed the camshaft sensor). so, since I had the crankshaft sensor changed I went ahead and changed the plugs and wires because I’ve had it for a little over a year and I didn’t know when or if they’d been done before and my truck has 220(ish),000 miles on it.
but after changing them (sensor, plugs and wires) it hasn’t started back up! I’m getting frustrated at this point.
So today I called the previous owner (I know him person and he’s a mechanic) to tell him what Goodyear had told me (because he thought it may have jumped time) and the previous owner told me to check the plug to the ECM because it had given him a problem before. (He apparently had sent it to the dealership and they couldn’t even figure it out) but come to find out the plug to the ECM wasn’t in all the way! It just looked plugged in.
so when I pick it up Monday from Goodyear I’m gonna check the ECM plug and also unplug the battery completely to see if maybe it’ll reset something and by the grace of god START!
You mention changing the plug wires. Have you verified the cap to plug order is correct? I am sure you did but this was one thing changed right before the issue appeared.
Verify and eliminate the most obvious and easiest things first.
Verify and eliminate the most obvious and easiest things first.
iamdub
Full Access Member
Yes this is the order of events except your #1 I had injectors replaced because I was having issues with it randomly not wanting to start-thought it was fuel pump but shop diagnosed it as 2 bad fuel injectors. ThTs why I had those changed. Then when I got it back. It had the code for the camshaft sensor. So I was going to change that and the crankshaft sensor. (Crankshaft got changed first) because it was broken off. (Never changed the camshaft sensor). so, since I had the crankshaft sensor changed I went ahead and changed the plugs and wires because I’ve had it for a little over a year and I didn’t know when or if they’d been done before and my truck has 220(ish),000 miles on it.
but after changing them (sensor, plugs and wires) it hasn’t started back up! I’m getting frustrated at this point.
So today I called the previous owner (I know him person and he’s a mechanic) to tell him what Goodyear had told me (because he thought it may have jumped time) and the previous owner told me to check the plug to the ECM because it had given him a problem before. (He apparently had sent it to the dealership and they couldn’t even figure it out) but come to find out the plug to the ECM wasn’t in all the way! It just looked plugged in.
so when I pick it up Monday from Goodyear I’m gonna check the ECM plug and also unplug the battery completely to see if maybe it’ll reset something and by the grace of god START!
Gotcha. With all the events and parts that have been replaced, the story can get confusing and mislead the diagnosis. Throwing a bunch of parts at it can bury the root problem, so we gotta know how it was, what was done and the direct result all in chronological order.
So, the plugs and wires were replaced at the same time as the CKP sensor replacement. It's common to get a couple of the spark wires mixed up, but they'd pretty much all have to be really mixed up to cause a no start or to not allow even an intermittent fire ("try" to start).
As @wsteele said- double check the firing order of the wires. You also can't rule out a faulty CKP sensor, especially if it was a parts store special. GMs needs quality parts and the cheaper aftermarket copies tend to cause problems. Whoever AutoZone uses for their bottom-dollar house brand of aftermarket electronics parts has been well documented to be producing some junk.
As for your P0340 code, that's the Camshaft Position Sensor ("CMP"). Since the CMP is in the distributor and this is the area involved when replacing spark wires, I'd check there first for faulty wiring. Did you replace the cap and rotor?
An engine needs fuel, air and fire. I'm sure it's getting air. Fire (spark) is questionable at this time due to your code(s). Once you can rule out lack of spark, then we can move on to fuel.
The story changes each time we get more info. You are probably not mechanically inclined, but thats OK. We can work with you as long as you help us along.
I asked for a spark check at coil and at Distributor coil terminal, was this done? Results?
Also asked for fuel pressure check results. On this Item- call the shop that changed injectors/spider. They should have done this before and after, at least before. Post the number they give you. Also Gently ask them if they reset the timing after distributor install. (The P-1345 in above posts). That will help to eliminate 2 problems.
Is sounds like problem started after Crank position sensor replacement. Was an AC Delco or Delphi unit installed? If other, that is your first Check. Replace with Delco.
Next step is Spark Check. A spark tester is $10-15 at AZ, so its worth it even if you have to buy it for them.
On having P0340, engine should still start. Crank position relearn not required on this engine- But P1345 must not be present. And a 50 mile drive cycle relearns everything. Keep posting we will get you goin again. Here is a diagnostic that will help your neighborhood mechanic thats helping you-
easyautodiagnostics.com
I asked for a spark check at coil and at Distributor coil terminal, was this done? Results?
Also asked for fuel pressure check results. On this Item- call the shop that changed injectors/spider. They should have done this before and after, at least before. Post the number they give you. Also Gently ask them if they reset the timing after distributor install. (The P-1345 in above posts). That will help to eliminate 2 problems.
Is sounds like problem started after Crank position sensor replacement. Was an AC Delco or Delphi unit installed? If other, that is your first Check. Replace with Delco.
Next step is Spark Check. A spark tester is $10-15 at AZ, so its worth it even if you have to buy it for them.
On having P0340, engine should still start. Crank position relearn not required on this engine- But P1345 must not be present. And a 50 mile drive cycle relearns everything. Keep posting we will get you goin again. Here is a diagnostic that will help your neighborhood mechanic thats helping you-
How To Test A Misfire / No Spark-No Start Condition (4.3L, 5.0L, 5.7L 96-04)
GM 4.3L, 5.0L, 5.7L Index of Articles
Last edited:
