Starting a new thread with ongoing issue now that a few possible solutions have been eliminated.

The shop had my truck all day today trying to identify why it keeps stalling after driving for 8+ miles. They checked every sensor and all were fine.
They did find there is a 5 volt draw affecting the PCM, but can't locate where from the normal diagnostics...

...I recently had my stereo replaced. Could the installer have done something to cause this 5 volt draw?

 

Possibly.

The CCD bus, the computer bus in your truck is 5v. It's a bit more complicated as this voltage is biased, but if the installer tapped the line it may be causing the draw. The system is supposed to "sleep" after a period of time when the key is off but some of the modules can keep it from going to sleep.

It would be a twisted pair wire harness, violet with a brown tracer AND white with a black tracer.

Some versions of the OEM radio do have provisions for the CCD bus connection.

 

I called the installer and they said it simply connects into the factory Chrysler plug, so there shouldn't be an issue from that. Plus, it only draws a small percentage of voltage.

The shop could not run all diagnostics to check the computer, they recommend I bite the bullet and take it to the dealership where they can test the computer more thoroughly.

185K on the vehicle (and thus computer), I know they usually last longer, but have heard of them failing sooner, too.
We talking $1,000+ installed and out the door?

Thanks for the answers and suggestions.

 

i think dans info is great. i think any electronic chip that the volts drop to low WILL act strange. most chips think any volt below 2 it will think it is o volts. but between 2-3 volts it doesnt know what to do and can act in many unknown was. that is in general. your mileage may vary. just what an electronic chip designer told me.

 

IF it is the PCM, you can get a rebuilt unit for a couple of hundred. You just give the company your info and they program it for you. Just plug and pray.

 

what company?

 

There are lots of places online, even Ebay.

 

Autocomputerexchange.com down in south Florida is supposed to be a very good quality pcm rebuilder. Maybe give them a try.

Jimmy

 

Just be aware that even new ones go bad I had a new OEM factory unit go bad in one month it was under warrantee so they replaced it again 7 years later still good.

Also be aware if you don't find why it went bad in the first place you may burn up every new unit you install that draw may just burn every new unit up so fix the underlying problem first.

Don't trust what the place that did your radio told you pull it out and inspect the job radio/security system installers are notoriously dishonest and sloppy at their installs as usually its young kids doing the installs.

Sorry I trust no one been burned way too many times by shops

 

Hanneman, I have a few thoughts on this problem. If all you had done was just a new radio installed it is pretty doubtful that the new radio is causing the 5 volt draw problem. The radio is not on the 5 volt PCI bus, it has a negative ground and two 12 volt power inputs, one for switched accessory power and one for constant 12 volt power so it retains the clock and radio presets and Blue Tooth info if your new radio has that capability.

I do not know for sure if a 98 has a Central Timer Module (CTM) but even if it did the CTM does not control the main power circuits of the factory radio. Where the CTM does come into play with the radio is on the steering wheel controls for the radio volume. I do not know if a 98 had that option, seems to me they did but even then the steering wheel radio controls do not operate on 5 volts or even 12 volts. They work through the CTM by providing inputs that are measured in ohms, not volts. There is a 2 wire connector behind the radio on trucks with steering wheel controls and if by some chance the installer tapped into one of those wires then maybe it could whack out the CTM and possibly interfere with the PCI bus that way. However, all it takes to install a new radio in a Dakota or any other Dodge is a matching wire harness that plugs into the factory radio and power connectors and has wires on the other end that you connect to the new radio. The harness makes it super simple and pretty much error proof as far as wiring goes because the wires for the new radio and the harness are all the same corresponding colors. Red for accessory power, yellow for constant power, orange for illumination, white for left front speaker, gray for right front speaker, green for left rear speaker and purple for right rear speaker.

The installation harness does not include a plug to plug into the 2 pin steering wheel volume control connector. You can pull the radio to see what was done, you will find a gray plug and a black plug, the gray plug has the accessory and constant 12 volt wires and also has the negative speaker wires for the front speakers on it. There are also wires for illumination of the factory radio on the gray plug but those should be taped up or otherwise insulated unless your new radio has an illumination wire. If it does the wire on the radio will be orange and should be connected to the orange wire on the harness. The black plug behind the radio has the other six speaker wires and a blue wire for turning on the factory Infinity amplifier if you have that option in your truck. Your factory radio had a silver braided ground strap bolted to the chassis of the factory radio, the strap and the outer shield on the antenna coax cable provide ground to the factory radio, but the braided straps are not a very good ground and do get contaminated over time and become even less of a good ground. The bad radio ground can cause problems with the radio but it will not interfere with the PCI bus. You can check the ground and re-ground the new radio to bare metal under the dash or even better under an existing bolt or nut in one of the kick panels. Unless the radio installer did some kind of funky ground for the new radio (again not very likely) the ground for the new radio has nothing to do with the 5 volt problem. I am telling you all this to point out that it is very unlikely the new radio has anything to do with the 5 volt problem. The only way that it could is if the installer made some really stupid errors in wiring the radio, but that just is not likely because it is super easy to install a new radio in a Dakota.

I am no expert but here is what I do think about this problem. I have a 2001 Dakota so in some ways my electrical system is different from your 1998. A lot of the basic functions are the same though as far as ignition, timing, and fuel management systems. I have a Dodge Factory Service Manual for my truck, again it is different for a 1998 but when I was reading my FSM trying to get info on my own stalling/shut down problem I read about the Crankshaft Position Sensor (CKP). The manual gives great detailed info on how the CKP works and how to R&R it. It also says that if the CKP fails the engine will not start and will not run. That is the important factor here, if the CKP is bad the truck will not run.

I read about the other sensors in the FSM too. I read up on the Coolant Temp Sensor, Intake Air Temp Sensor, Camshaft Position Sensor, IAC, TPS, and MAP sensors. Those are the main engine management sensors and they do run on the 5 volt system PCI bus. However the important difference is that when reading about these other sensors, nowhere does the FSM say that the truck will not start or run if one of these other sensors fails.

What I read in the FSM and the info TNtech gave us about the CKP failing when it heats up gives me very good reason to believe the CKP is the cause of the 5 volt stall/no-start problem. I would suggest that maybe you can either do it yourself or get the shop to replace the CKP and see if it solves the problem. Even if the CKP is not showing as being defective at the shop, the truck shuts off after you drive 8 miles. So I think it is hard for the shop to duplicate the problem and they will say if they can't duplicate it they can't fix it. Replacing the CKP may be the solution.

Let us know how it turns out.

Jimmy