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

[BadAxe]

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.

[grancito]

That problem is the expensive thingy that is at the top of the accellerator pedal. It has like a toaster element in it that wears out where the contact rubs.

[Chevylover]

Service Throttle Lamp is the same as SES or MAL lamp. Yours is a 1994, so you can blink out the codes by your own. Check which codes are stored, tell us and we'll see, what the problem is or could be. Send you a PM how to blink out the codes !


Cu,
Sven

[BadAxe]

As stated it doesn't want to share any codes with me, just the resounding 12. 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. The stalls were at dead stops not runnung down the road like with the PMD. Ignition switch has been sugested, but there are 0 starter issues. I'll finish remote mount of new PMD today.

[trukdoc]

...switch "problems" started in 95 with "new"design switch...94 has same switch gms used in truks since 70s...I would lean towards grants idea of throttle potentiameter...OR wiring to pedal assembly...clicking was circuit breaker...if you run with your foot in basically same place then contacts will wear over time and can result in an intermittant short...

[BadAxe]

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.

Truckdoc, your theory makes perfect sense to me, considering the Toyota like symptoms.

[BadAxe]

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 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?

[trukdoc]

...sits on end of rod from key cylinder..."new"ign.sw. should be in off position...align opening in assembly with end of rod and tighten down...there is a small amount of adjustment available to center key at off/lock position...round switch at 9o'clock is dimmer switch...jd

[BadAxe]

Well it finally stopped cooperating. On the way to peruse the junk yards it died just three miles from home. It will crank but getting no SES, STS, or GP lights at all. One of the most frustrating parts is that it cost me $85 just to get it towed back the 3 miles. Dropped in spare PMD and no change. Pulled ECM and nothing noticeable. Need help fast.

[BadAxe]

Grounds cleaned, fuel flowing, engine cranks, fuses under dash good, and no fusible links gone bad. Still no SES, STS, GP lights.

[BadAxe]

Went to overhaul grounds, still going to, to humor myself turned the key and it started up. A little reluctantly but started. Now off to rebuild the grounds.

[trukdoc]

...the relays that power the ecm/pcm...

[BadAxe]

Rebuilt grounds and it has run great for about a month, but last week while at a stop light it died. Did this about three times in a row. It's doing this at very low idle while in gear almost like it is bogging down. Just replaced the OPS with a fresh oil change and lift pump tested good.

It has been giving a SES light,code 36, for about ten seconds right after start up when I make a short stop- run into store for milk, soda, parts store, etc.

[CAdiesel]

Was the PMD you relocated behind the bumper a NEW one? I had a code 36 when my last PMD went out (I also had a mess of other codes that haven't come back since replacing).
Did you ever do anything with the accelerator pedal?