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Service Throttle Soon......What the?

Badaxe

Badaxe

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Ok Y’all,
Here is the situation, while driving today the truck stumbled like it used to when the PMD went bad. This time it never died though. The power dropped off and the “service throttle soon” and check engine came on simultaneously with a relay sounding click coming from under the dash. I let off the throttle, lights go off, and it drives fine for another half mile before starting the whole process again (especially near 50mph). As I neared home it stalled once and then again in the front of the house. We swapped vehicles and continued our errands for the day. When we got home a few hours later it gave no codes and fired right up. We have made several road trips lately and my commute to work is 50 miles round trip with no problems what so ever. Fuel filters are new and original PMD in use right now. I need to figure this out as quickly and economically as possible. Thanks in advance.
 
Where is the PMD mounted? What brand is it? Do you have a known good one to try?
 
Right now I'm plugged into the stock IP mounted one. I've got the harness and a couple spares to mount behind the bumper, but forgot what gel/grease to put between new PMD and heat sync. The thing that is throwing me off is the "throttle light", when the last PMD went there were no warning lights at all.
 
Thats whats making IGN module stick out in my head... Its a common wear item, and when mine went I clearly remembered the throttle light, vs no throttle light when I had PMD issue.

Eventually my truck didn't start, and I could tell because when I turned the key, I didn't get the proper lights. I would get no WTS, but that throttle was there... It was odd.
 
I had throttle light and limp mode, transient code, lots of noise, low power, all that stuff.

If you shut the truck off on the fly (scary!) and restart, it was fine again.

Dying PMD.

What brand of relocate do you have, where is it mounted, etc?
 
I used the silver stuff that's used on computer processors to the heatsink. It worked fine. Seal around the PMD with some sillicone after it's mounted.
 
The stalls were at dead stops not running down the road like with the PMD. Matt, not to discount your suggestion of the Ignition switch, I will look into it, but there are 0 starter issues that lots claim. I'll finish remote mount of new PMD today.
 
Arctic Silver 5 is the one most people use. It is available at Radio Shack or any electronic store like BestBuy, etc. There are other type also which is probably sufficient for PMD like Arctic Ceramique.
 
Your issue here, if you don't have any codes set and stored, is going to be narrowing it down to best probabilities by careful diagnostics. Resist the temptation to just throw parts at the problem, but understand that this could be a number of things.

Answer people's questions, consider the obvious AND not-so-obvious symptoms, look for all-and-any related causes. About the only way to be sure of an issue like this is to narrow it down, triangulate as much as possible, then try parts from a much shorter list. Start cheap.

Fortunately, you are in the best place on the 'net for stuff like this.. these guys will help you to track down your problem!
 
Well I finished the behind the bumper PMD and so far it's running just fine, possibly better considering I was running the 16 y/o stock one. I won't be able to get it up to speed and warm till next week. So we will see.
 
Badaxe said:
The stalls were at dead stops not running down the road like with the PMD. Matt, not to discount your suggestion of the Ignition switch, I will look into it, but there are 0 starter issues that lots claim. I'll finish remote mount of new PMD today.
Click to expand...

Expanding on ignition switches be it the problem or not.

Starter is only one of many contacts in an ignition switch. There were 5 contacts in the last (2007) switch I tore apart. The contact that failed powered the computer. It browned out the computer giving false engine codes and weird running issues - started just fine. The switches do not totally fail rather cause a high resistance connection and drop voltages below operating spec: like the OPS switch failure does.
 
Update: Still Problems

Well it seemed to run great for the short little trips around the area. Then on one of the latest trips it died, just a few miles from the house, put it in neutral and when the ignition was cycled the GP light and STS light did not come on. I had the whole family with me and was able to coast to the nearest parking lot. Cycled ignition again and it started right up, still no codes given, but for good measure the spare PMD was plugged in. Ran great for a day or two and then started giving a code 36 at start up. Thurs morn on way to work power dropped off, didn't die, STS light flashed for a second, and then ran like nothing happened. Yesterday I changed the ignition switch for good measure. It died twice this morn during warm up after idling for a good while and fired back up each time. Ran fine coming home but flashed the STS a couple times. This afternoon it died at a stop light. Again when ignition was cycled no GP or STS lights until 30 seconds or so then got lights back fired up like nothing happened. As of right now the only code it gives is the resounding code 12.

Side notes: speedo has been possessed for a while. Is there a proper way to install ign switch and what is the round sensor/switch mounted next to it?
 
It certainly sounds like you have a PCM power problem, which leads to IGN switch, but could be an iffy ground as well. If you want to pull PCM out and check ground and voltage sources with a multimeter I can post the pins they come in on. Or perhaps a PCM problem. Perhaps pull glove compartment out and disconnect PCM, inspect pins and wires, open rear door to inspect the EPROM (chip) and then put it all back in. Perhaps the previous owner had a chip in it that they removed or whatever and didnt get good contact.

Redo the grounds on the back of the passenger side, at the rear of the head/intake. You should find 2 on top and should be another on back of head too.
 
As per your question about the cable (in another post) I would highly suspect it to be a Chinese cable. Try pluging PMD straight into original pig tail coming off pump as a temp test.
Inspect cable for loose or burned pins/sockets and even smell it and see if you can smell a burned smell.
I will tell you this also, there a atleast a couple dealers in FL that sell on ebay and They bought my cable and use it in their pictures on ebay, BUT! will send you a cable made in China. One even says his is made in USA, but I know for a fact it is a Chinese cable.
Some things from China are great, those cables are not one of them.
 
I will go back to manifold location with the new PMD in the morning. It still throws me off a little because of the identical signs and symptoms with the NEW relocate and the stock PMD.
 
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