First CEL - P0500

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So tonight we chased continuity. We had continuity from the VSS to the cluster and from the cluster to the ECM. Last piece in the puzzle was the ECM. I called a friend with a '98 over and we swapped ECMs to see if my ECM in his truck would trip a code and if his would clear mine. Well, we couldn't get the immobilizer to program, either after sitting for 30 minutes or by forcing it with a Toyota laptop.

Now the strange stuff. We put my ECM back and figured that's got to be the culprit, everything else had been ruled out. Well, I buttoned up and on the road home I tested the cruise - it works. No CEL the whole way home, even with 4 stops and starts. Before the cruise wouldn't work (even without a CEL) and the CEL would come back after two starts and not a long amount of time.

So, theories are that we'd never had the ECM totally off battery in all of this and maybe pulling it off power did something to reset it. Another theory is that something in the ECM, harness, or connector was loose and made contact again with our dinking around with it.

I HATE problems that resolve like this. I fully expect the CEL to come back on in the next day or two, it just can't be that bizarre of a fix. So, sowbug, try pulling the + off the battery for a half hour and see what happens.
 
Trunk Monkey said:
So tonight we chased continuity. We had continuity from the VSS to the cluster and from the cluster to the ECM. Last piece in the puzzle was the ECM. I called a friend with a '98 over and we swapped ECMs to see if my ECM in his truck would trip a code and if his would clear mine. Well, we couldn't get the immobilizer to program, either after sitting for 30 minutes or by forcing it with a Toyota laptop.

Now the strange stuff. We put my ECM back and figured that's got to be the culprit, everything else had been ruled out. Well, I buttoned up and on the road home I tested the cruise - it works. No CEL the whole way home, even with 4 stops and starts. Before the cruise wouldn't work (even without a CEL) and the CEL would come back after two starts and not a long amount of time.

So, theories are that we'd never had the ECM totally off battery in all of this and maybe pulling it off power did something to reset it. Another theory is that something in the ECM, harness, or connector was loose and made contact again with our dinking around with it.

I HATE problems that resolve like this. I fully expect the CEL to come back on in the next day or two, it just can't be that bizarre of a fix. So, sowbug, try pulling the + off the battery for a half hour and see what happens.
Click to expand...

Trunk, you must be a mind reader! I just logged in to see if there was any more replies on this subject....and bing! I'm glad its working and hopefully it is cleared. Thanks for the tip and I will try that before I go to the stealer! Wish me luck!

:cheers:
 
man, I feel for you. hopefully it was just poor contact with one of the pins and now that you've reseated it the problem will be solved.
 
I was getting a code for a transmission issue, which turned out to be related to the speed sensors. Some contact cleaner on those connectors fixed it. Might work in this case. :meh:
 
Skidoo....the speed sensor connectors?

I tried the battery trick - unhook the positive connection for 30 mins. Worked briefly, but the damn CEL is back on.

SONOFA!!!
 
Yes the sensor connections on trans and t-case. These connectors being under the truck get water and road chemicals splashed on them.
Some dielectric grease on sealing surfaces is recommended on reassembly.
 
Word back from Stealer....Combination Meter. $950 parts and labor....he said part needs to be ordered with mileage programmed in. Plus the 2 hours of labor to diagnose the problem. Said he'd knock off 10%.

Thoughts?
 
I got mine off Ebay for $125. Odometer was 10k off, but it at least told me it wasn't the speedo amplifier. You could do it pretty easily, it's one trim piece, unplug one connector, 3 screws for the trim on the steering wheel, and 6 screws for the cluster.

But yes, if ordered from Toyota they pre-program in your mileage so there's nothing hinky. What'll they do if the cluster doesn't solve the problem?
 
Trunk Monkey said:
I got mine off Ebay for $125. Odometer was 10k off, but it at least told me it wasn't the speedo amplifier. You could do it pretty easily, it's one trim piece, unplug one connector, 3 screws for the trim on the steering wheel, and 6 screws for the cluster.

But yes, if ordered from Toyota they pre-program in your mileage so there's nothing hinky. What'll they do if the cluster doesn't solve the problem?
Click to expand...

Probably hit me up for more $$!

:bang:
 
I reset the CEL a couple of times and it would come back after a while.
BTW took it to my dealer to see what they came up with, and the solution was to replace the transmission for $3600. So in my case saved a little with some contact cleaner and the dielectric grease.
Had good results with Bullfrog Contact Cleaner. No CEL since.
 
Skidoo said:
I reset the CEL a couple of times and it would come back after a while.
BTW took it to my dealer to see what they came up with, and the solution was to replace the transmission for $3600. So in my case saved a little with some contact cleaner and the dielectric grease.
Had good results with Bullfrog Contact Cleaner. No CEL since.
Click to expand...

Skidoo...what are you talking about putting the contact cleaner on? The Vehicle Speed Sensor?....and where is it located?
 
Believe there are two speed sensors. The one on t-case and one on transmission driver side (don't remember if 2003 has dipstick) if so follow it up a bit and should be a couple of wires with a connector to a sensor. Pull the connector and clean contacts on both sides. Same on t-case one.
 
Well, it's back. Came on totally randomly when I started the truck after getting a big gulp. I tried the disconnect battery and ECM trick, didn't work. It's almost exactly a year later so that makes me wonder if it's heat related with summer. Only other thing that's changed is I did my brakes two weeks ago, so maybe a wire got stretched or something. My Toy tech friend thinks it's a loose terminal or wire pulled too tight to make contact.

And of course, we're driving to Disney in a week - that'll be fun with no cruise.
 
Had my first coil pack go Sunday, that was fun. It wouldn't throw a code, just blink the CEL if I gassed it at all. With a long road trip coming up I decided to take it in for the misfire and p0500 - 1000 miles of highway with no cruise control sucks.

A block away from the dealership the code locks, p0303. Could have done it myself for $80, but had them do it since they were in there anway. With the p0500 the tech comes back with there's oil in the VSS top cavity by the electronics. They say they've cleaned it out, it's all good, but recommend eventually changing the VSS ($250 for part). I pick up the truck and a block away notice the cruise won't set. Two blocks away the CEL comes back on.

I get the truck home and check the sensor. Yes, there is oil in the top portion, but, there's a spiral cut on the shaft of the sensor, clearly to auger oil up into the rotating top, and the electronics are all sealed. So, it's supposed to have oil in it. Also doesn't jive with the fact that I swapped a VSS from another 100 and still have the problem.

I followed the FSM and rotated a rear tire while reading voltage at the wire at the ECM. FSM says it's supposed to vary between 4-6v as the sensor rotates, I was getting .2-.9. So, the ECM isn't getting enough voltage to read a good speed. That traces back to the combi meter (which I swapped with one off Ebay) or in a junction block between the combi and ECM that maybe has some corrosion or a loose wire.

Going back to the dealer in the AM, we'll see what happens. I bet first thing they're going to want to do is replace the VSS.
 
Final update (I hope). Here's what's occured to date:

- took truck in after the above post. They checked the VSS and connections. Cleared code and gave me the truck back. I got two blocks and tried to set the cruise, it wouldn't. Pulled over, turned truck off and back on (CEL usually requires 2 start cycles), CEL came back on a few minutes later. Called dealership back, let them know.

- drop truck off following morning. They run tests and chase it to the ECM. We were leaving on a trip to Disney the next day, so they ordered the ECM. Toyota has a program with the vehicles with transponder keys that if you loose all of the keys to your vehicle they will replace the ECM once for free (you pay for labor and 2 master keys - $300 vs. $1400 for ECM part alone). So, I "lost" all of my keys while at Disney. Dropped truck back off after trip and they replaced ECM. CEL came back. At this point they scheduled the truck to be seen by the Toyota field services tech when he was in Salt Lake next, 2 weeks ahead.

- drop truck off for field tech visit. He gives the techs a list of things to chase down, all of which show good. Dealership ends up keeping the truck 3 days and a few different techs begin chasing things down. I guess it became kind of a "thing" to figure out what it was.

And the end result - bad ground in the dash behind the cluster. Service manager said it's probably been that way since the truck was built, it's just had enough time to work loose enough to drop the voltage signal to the ECM. I've got to give props to Mark Miller Toyota in SLC and Bruce in Service. The total tab could have been a lot higher than they're charging me, but they've been awesome about not tacking on things which didn't achieve a fix.
 
Thanks for this thread. I’m going to check that now, I’m having similar issues. Not seeing any evidence of water damage.
 
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