Codes on a '95

[winemaker]

Howdy all: a customer of mine is having problems with his '95 automatic 6.5 These are the codes:

99 pedal position 2 5 volt ref. fault

29 glow plug relay

46 malfunction indicator lamp

49 service throttle soon

The symptom is a hesitation or slipping between 2000 and 3000 rpm under load in overdrive and 3rd gear, moreso in overdrive. Any suggestions, please?

Thanks!
Brett

[JohnC]

Multiple unrelated codes usually means a bad connection somewhere. Look at the ground point on the passenger's side of the intake manifold at the rear.

Of course the real problem could be plugged fuel filter or bad lift pump and the codes red herrings.

[winemaker]

Thanks John, I'll pass that on to him. Much appreciated
Brett

[Robyn]

As john mentioned, unrelated codes are in many cases connection issues.

Be sure that both battery grounds are good as well as both ++ cables too.

The dual battery setup on the 95 uses the RH battery connection for the starter and the left hand side for the chassis feed.
If one of the grounds goes henhouse things get hinky.

Be sure that the chassis feed (junction box behind the ABS) has a good 14V supply with engine running.

Also as John mentioned the grounds at the rear stud on the intake manifold.

The codes need to be cleared out and then see what comes back.

None of those codes translate to a "Slipping condition"

BUTTTTTTT a fuel filter can cause issues that can resemble what you describe :)

On a 6.5 the fuel filter and the PMD are always in the gunsights when diagnosing issues. (Well almost) ;)

Example

The other day I was coming back from Portland to the shop (30 miles) and slowed as I came off the freeway. Started to go as I made a right turn and the thing stumbled and missed for a bit and then was fine.

The next decel and RH turn, same thing.

Drove the rig around a bit but it seemed to be fine going down the road.
Long slow down and RH turn, miss like crazy.

Issue
Plugged fuel filter. New filter installed, all fine.

The codes you listed may be old stored codes that have never been removed.

Clear them before doing any more daignostics.

Definately check the battery cables.
I can say without doubt, if the cables are the factory ones, they are shot.
The cables corrode under the red/black jackets and in the strands under the crimped eyes.

I had a ground on DaHooooley that the engine block end had no connection to the battery end.
Replaced cable and was fine.

This stuff can't be seen upon visual inspection.
The ECM just goes nuts when the grounds and or voltage gets hinky.

Another little issue can be an alternator thats not supplying good DC current.
If a diode has failed and the thing is producing a sort of "AC" current this can send the ECM into a "Tizzy Fit"


Keep us posted


Missy

[winemaker]

Thanks a bunch, Robyn...I'll pass this info on, too. I'll let you know what happens.
Brett