Replacement for Throttle Actuator Control - Vortec 8.1

[zogthegreat]

Hi everyone!

I have a Vortec 8.1 on my 2004 Damon Challenger motorhome. I was driving it today and suddenly, the engine lost power and the check engine light came on. After turning the engine off and restarting it, I was able to make it back home, although I had the same power loss 3 more times over about 20 mile ride. I hooked up my OBDII scanner, (ELM scanner using Torque as an interface), and I retrieved the following codes:

P0120 - Throttle/pedal sensor switch "A" circuit
P0220 - Throttle/pedal sensor switch "B" circuit
P1516 - Powertrain
P2108 - Powertrain Actuator Control Module
P0107 - Network

Based on the information that I have found Googling, it seems that I need to replace the Throttle Actuator Controller. Here are my questions:

1. I noticed that the Throttle Actuator Controller is rivited on the throttle body. Is it possible to drill out the rivetes and replace only the TAC?

2. Does anyone have the part number for the TAC? I'm going to try to remove it tomorrow, tight fit to get into there!

Thanks

zog

[UFO Pilot]

When the same thing happened on my GM pickup. they had to replace the entire throttle body. It was a very costly repair. My truck doesn't have the 8.1 but I was told that they are all that way.

[garyspang]

Both are out, and you could still drive it home. Very strange. I would put a multi-meter to use and check it all out for continuity, resistances and voltages. After you remove the rubber-like intake pipe, you may be able to manually rotate the butterfly valves and make measurements. If not then voltage applied to the servo-motors will do the same. Check the actual voltage used on the motors with the ignition on while changing the foot throttle position. Take your time and write down the results of your measurements to assist you in actual failure analysis.

[Brazel's RV Performance]

The TAC module is not mounted on the throttle body, that is just a position sensor. The TAC module is bolted to the steering column support on the left side. Here is a picture of it

[zogthegreat]

Originally Posted by Ultra RV Tech

The TAC module is not mounted on the throttle body, that is just a position sensor. The TAC module is bolted to the steering column support on the left side. Here is a picture of it Attachment 120753

Thanks! That just save me money, plus the throttle sensor is a PITA to get to!

[zogthegreat]

OK, I pulled the unit, (thanks again Jon!) and here is what it looks like:



The first thing that I noticed is that the foil had already been pulled back, not sure if the previous owners had had this problem. I have put about 2000 miles on the coach since I purchased it last July and I haven't had this problem. The coach has been parked since November. Any suggestions as to why it would suddenly go bad like this?

Also, the number on it is TMD1-160B1, but that module seems to be for the GMC 4.3. 4.8,5.3 and 6.0. Can I/should I replace it with a TMD1-160A1, which is for the Vortec 8.1?

[DonL]

Sorry to see that you're experiencing the same problem as me. Ours is a 2003 Allegro Bay on a 2002 W22 Chassis. As best I can tell, the correct part number is 25347057. I found a few replacement modules at varying prices. I ordered one that I found on e-bay (best price found for a new module).

The next best deal I found was at Smitty's Automotive and RV. Their phone number is 419 478 1309, Ask for Scott. He has one that has been used as a diagnostic aid, but otherwise is new. His price is $203.50 including shipping.

I also found indication that some of the Chevrolet part numbers (lower cost and more readily available) might serve as replacement but so far have been unable to confirm that. So I elected to stay with the Workhorse part.

Others I found were priced north of $350 and you can find them via Bing search.

Good luck in getting yours back on the road, and I'm hoping the new module takes care of my problem.

DonL

[Brazel's RV Performance]

Originally Posted by DonL

As best I can tell, the correct part number is 25347057.

That part # is good for 2001-2002 chassis but the OP has a 2004 which would require part # 12588924

[zogthegreat]

Originally Posted by Ultra RV Tech

That part # is good for 2001-2002 chassis but the OP has a 2004 which would require part # 12588924

The number that you listed, 12588924, is for the TMD1-160F1. Do you know if this is the original part that I need? I tried to contact Workhorse today, but the guy couldn't find the information, (I'll try another Workhorse shop tomorrow).

I found a refurbished throttle with a new TPS for $120.00, so I will go ahead and grab it. I can find used TMD1-160A1's for about $50.00 and new TMD1-160F1's for around $200.00. One thing that I noticed is that the TMD1-160A1 seems to have an extra part, (red arrow in the pictue), that I don't have in my setup.

[Brazel's RV Performance]

I'll have to look at one we have in stock to see what other #s are on it.

You'll notice in that picture you just posted that the throttle pedal and sensor is also different from what you have.

[zogthegreat]

OK, after spending the morning calling 6 different Workhorse service centers, I found someone who could find the part number. He told me that it is the 12588923, (TMD!-160A1). I then called GM Parts Online and they told me the same. Unless anyone has different information, I'll go ahead and order the 12588923.
(I trust my fellow forum members more than someone who really didn't seem to be that knowledgeable!)

[Brazel's RV Performance]

What is the last 8 digits of your VIN? The 12588923 is listed for GM SUV's, not the Workhorse chassis WHICH IS different. Unless you order 12588924 I think you are going to continue to have issues......

[zogthegreat]

Originally Posted by Ultra RV Tech

What is the last 8 digits of your VIN?

The last 8 of my VIN is 43386162.

Originally Posted by Ultra RV Tech

The 12588923 is listed for GM SUV's, not the Workhorse chassis WHICH IS different. Unless you order 12588924 I think you are going to continue to have issues......

Yeah, that's why I thought it would be best to wait!

[Brazel's RV Performance]

12588924 is the correct TAC module for your VIN. I double checked ours and the stamped manufacturer # is TMD1-160F1. This TAC module is only used in medium duty application including Workhorse as they have a different throttle pedal position sensor than the light duty vehicles that take the 12588923.