Dianostic port Chevy chassis 95

[Charlie 5320]

I've got a 95 Damon Challenger on a Chevy chassis. Having an intermittent check engine light. I've been al over the wiring harness trying to find the adl link plug. I've been getting a lot of different answers, but none are right so far. I've talked with Damon, no luck there. Workhorse can't help, built before they purchased from gm. My local Chevy dealer don't have a clue because they don't work on med trucks.

I've fallowed the harness from the computer under the dash and under the hood. No obd1 or obd2 port, but all the mechanics I talk with say it is on the left side of the stering colum. The only connector in that location is a grey connector that looks like a male connector fits in. I have looked at al the paper work that came with the coach, and found where a Chevy dealer did a dianostic check on it back in 2001. That mechanic no longer works there. I've been told it was a change over year and can be obd1 or obd2. My buddy just bought a 96 Storm a few weeks ago, and we were looking at his. His has an obd2 port but when we hook up his snapon scanner it won't read anything. It works on our 2005 Chevy pick ups.

Anybody got any ideas? Is there a part of my harness missing? Maybe when the mechanic worked on it in 2001.  I've owned the coach for 4 years and have always done my own work, tune ups and service.

Thanks Charlie

 

[Charlie 5320]

Well after a lot talking to shops regaurding my problem, I got on E-bay and found some service and electrical manuals for my coach chassis. Once I found out what color the wires were going to the adl port, I started at the ecm and traced the loom back till I found that set of wires. Followed them, and sure enough there was the port, but it looked like it was pluged into the front of the steering colum. It wasn't, it was just stuck in there. These books already paid for themselfs.

 

[WILDEBILL308]

Glad you found it. Now did it tell you what your problem is?

 

[Charlie 5320]

Idle air solenoid. Haven't worked on it yet, but the procedure is in the book. I have to dig out my vacuum pump. It'll probably be a vacuum leak, that I can't hear. Ears aren't so good anymore.  Too many years working without ear protection and around my race cars with open headers I guess.

 

[Charlie 5320]

Update.    I ended up buying a used scanner off of e-bay. Found out the idle was too fast because of a bent throttle cable bracket. It was idleing too fast and the iac was out of the circuit, the ecm couldn't control the idle, so it set the service engine light. I must have bent the bracket this spring when I was laying on the engine removing the alternator.  Now on to another problem. Chassis doesn't charge the coach batteries. 

 

[mylo]

Update.    I ended up buying a used scanner off of e-bay. Found out the idle was too fast because of a bent throttle cable bracket. It was idleing too fast and the iac was out of the circuit, the ecm couldn't control the idle, so it set the service engine light. I must have bent the bracket this spring when I was laying on the engine removing the alternator.  Now on to another problem. Chassis doesn't charge the coach batteries. 

I have that same problem with my 1990 Chevy G30 chassis. Clueless on where to begin. Please share any knowledge nuggets you discover in troubleshooting.


Mylo

 

[John From Detroit]

I can tell you where to begain.. You will need a Multi-meter.

Find the battery isolator soleonid,  Just where to look veries from one body to another so I can't help you there. But it often looks a bit like a ford Starter Solenoid, works differently however.  You are going to check for voltage (Ending off) on the two BIG terminals,  You should see chassis battery on voltage on one side and house battery voltage on the other.

The small terminals should show zero zero

Personally I'd hook a test light across them but your muliti-meter can be used too, it does not matter which lead on a modern digital meter goes to which of the two small terminals.

Have partner start engine.. watch meter for like 2 minutes. at some point it should show voltage. You should, also hear/feel the solenoid pull in, If so,, then go back to measuring voltage on both of the big terminals (with respect to ground) same both sides, good solenoid, still different (not a tenth of a volt is not enough differnce) bad solenoid.

No voltage to the small terminals bad control circuit.

Note, voltage to small terminals may be transient, (That is may come and go quickly) or it may be constant when engine is running, which depends on the solenoid.

That does not solve the issue or the tests (before starting) do not match what I told you to expect.. Post results and we go to next step.

 

[mylo]

Thanks, John. I guess I did one of these tests... With the van running, I checked the voltage on both big lugs. The chassis side was a lot higher. The house side read the same that it did, back on the converter.

I didn't notice any small lugs. I'll check tomorrow.

Let me just rephrase. So with the meter connecting both small lugs and the engine off, I should see nothing. Then after two minutes or so, I should see some voltage between them. It might come and go, or it might be steady - after which, both sides large lugs should read the same.

I suppose the "AUX START" button does the same thing? If someone holds it with the engine off, I should see some voltage across the small lugs (transient or steady), hear the click, and get the same reading off both large lugs (assuming the solenoid is OK), right?

Thanks.


Mylo

 

[Charlie 5320]

Thanks John, I'll tackle my problem Sat. as it is getting dark when I get home from work.  Mine has 2 of those solenoids very close together. I know 1 of them works, the one that works from the momentary switch. These coachs should come with a wiring schematic from the factory. This thing is starting to be almost as much trouble as my old Itasca was. I'll get through it this winter. Just got done with my tv upgrade, and new tires. Now if I can keep the rodents out I'll be happy. I got the books and a Mac profesional scan tool for about 1 hours labor over at the service center.

 

[Charlie 5320]

Update, John thanks for the info. I found out that my battery isolaters appear to be working, but there is another part on there, don't know what it is. Looks like maybe some kind of circuit breaker. little black deal with 2 terminals, one side is house batteries power, the other is power from the chassis. Nothing to control it, so its job has to be just pass power, and open if there is too much draw. I guess I'm not understanding how this system is supposed to work. If I have the generator running going down the road what keeps the chassis isolated from the the house ? Is this little black deal a diode? If so it is either bad or wired incorrectly. I'm going to have to fine a wiring schematic on how these things a supposed to be.

 

[mylo]

92GA -

FWIW, I have a one of those, too - AND a some old plans from the manufacturer. My coach is so old, they don't care anymore. They gave me whatever they could find, including plumbing, structural, and low and high voltage electrical.

I'll post pictures of the device I think you are talking about. From what I gathered from my diagram, it is indeed some sort of solid state circuit breaker. It's not clear to me if is "reusable" once it blows. Maybe you just replace it. I tested mine for continuity, and it's good.


Mylo

 

[Charlie 5320]

I looked on e-bay and it looks like a automatic circuit breaker to me. I can't see any markings on the one on my coach, so I don't have any idea what to buy if it is bad. It has to be open or at least it is not passing full power, because I have different voltage on each side. I'm going back out in a bit and pull the wire off of one side and see if it's got a path.

 

[mylo]

Well, I found my problem. Next to the solenoid there is the breaker, and next to that is another relay. Out of luck, I traced one of the wires leading from that relay. It was a short jumper that was just flopping around. Nearby was a crimp ring attached to chassis ground. It looked like it was chewed. I touched the flopping wire to ground with the van running, heard the solenoid click, and immediately got the same reading on both sides of the main solenoid. I will post some pictures later, when I log in with my laptop. Maybe your coach is wired the same, and it will help you with your problem.


Mylo

 

[Charlie 5320]

Found my problem too. It was the 50amp circuit breaker that was bad. I was able to read the info off of it when I got it out in the daylight. Just ordered a couple of them. Still think there should be some kind of diode in the system for when you're running down the road with the genny running. The way mine is wired 1 solinoid is hot when the key is on passing power when the engine is running. So if you have the genny running both systems is trying to charge the batteries, just don't seem right. I'm going to be looking at this some more.