DmaxMaverick follow-up - Glow Plug SES

[dogren]

DmaxMaverick,
Thanks for coming to the aid of a rookie with a glow plug SES code. I reviewed your earlier post but, as a rookie, I are not too smart. Can you be more specific with the location of the controller? Getting the initial overall voltage reading to begin the diagnostic process for the plug by plug is escaping me. Is there a diagram and a procedure

[DmaxMaverick]

No prob!

The controller is at the rear/left (driver's side) of the engine, over the valve cover, close to the firewall. There is a large, red battery cable connected at the left side. The connectors are on top, at the rear of the controller. The conectors are inline, 4 pole plugs (like an inline trailer plug), and are L/R correct, meaning the left connector is the left bank, etc. White set is left, red set is right....doesn't get more simple than that. There is nothing between the connectors and the plugs, so no resistors or relays to consider when testing. A diagram isn't really necessary, as the entire circuit (except the PCM circuit) is exposed, and pretty obvious.

The voltage reading needs to be taken by a scanner, or Predator programmer, as it is monitored by the PCM. When checking the connectors, you only need to check continuity between the connector poles, and ground, as the other end of that wire is connected directly to the plug. You can check the ohm's, but that would be splitting hairs. A closed plug will [usually] be good, and an open plug will be bad.

I, too, heard the cost of relays was about the same as the entire controller.

How were you able to pull the P0380 in the first place? If you have access to a scanner, check the GP voltage on a cold engine during the Wait To Start cycle.

At any rate, I snapped some pic's of the controller/connectors and uploaded them to my Webshots album. Just click on the "Truck Stuff Pic's" in my sig. and select "GP Controller".


On edit:
The above is partly specific to CA emmissions trucks. Read later posts for updated info.

[ 11-04-2005, 06:51 AM: Message edited by: DmaxMaverick ]

[dogren]

DmaxMaverick,
Wow, thanks for the help. Very cool site. The controller has been located but it is not like the one pictured. There are no flat, 4-wire plugs on top like pictured. My rig is a '01 Chev vs. your GMC. Issue?? The code was pulled with a buddies scanner. He brought it in today and we'll see if it can provide the initial voltage reading (it's not a Predator). We're also gonna dig a little deeper and try to find where the plugs do come in, perhaps they're on the underside??. I'll keep you posted. Thanks again, D

[DmaxMaverick]

Mine is a CA truck, and the CA GP circuit (emmissions) is different than non-CA trucks. Can you snap a pic of the controller you have and email it to me? dmaxmaverick@thedieselpage.com

Interesting. The diagram I have doesn't show anything that looks like my controller (??), but it does show a different controller for CA and Federal emmissions. CA trucks have a "controller", and federal trucks have a "relay". Either way, there should be a connector for the harness. Follow the harness from the GP's to the relay.

OK. Found the federal emmissions diagram. It appears there is a single, nut-fastened connector for each bank. This would complicate the individual plug testing procedure, meaning you would have to do it like I did it the first time, one at a time, removing the nut from each plug. Guess this is one time I was fortunate to have CA emmissions (usually gets in my way). According to the manual, all other diagnostic and testing procedures are the same, as are the monitored voltages. This may explain the prices regarding the controller and relay??

[dogren]

More info as folows:
Scanner is generic and only pulls the codes - does not have a GP voltage option. Traced wires from the controller - found four, 4-prong plugs - 2 each on each bank (16 wires). Plugs look identical to the ones in your pics and lead to two spots on top of valve covers - both sides. Are GP's under covers? Wire colors are green and brown. Could only access 2 of 4 plugs (2 buried). Un-plugged - meter shows continuity on two legs - twice (green-to-brown, twice, for one plug). Same on other plug. Did I just check 4 GP's? Popped cover off controller. Two relays laying on top. Only one clicks when you turn the key on/off. Does this indicate one relay is bad? Why can't it be easier for a rookie? D

[dogren]

This one is stumping some guys here in MPLS. Any ideas?? Thanks D.

[DmaxMaverick]

There's not a whole lot to the system to be "stumped" about. Have you checked each plug? Remove the wire and check continuity for each one if you have to. If all plugs are good, the relay needs to be replaced, according to the diagnostic table. If you are not having starting issues, it is likely just one or two bad plugs. If your plugs aren't working at all, your starts will be rough and smokey, and gets worse as it gets colder.

If you need the diagnostic table, I can email it to you. I can't post it publicly. I strongly suggest you get your hands on a scanner that can read real-time data. Someone in your area must have a Predator. I'll stay with you 'til you "gitterdun", but the distance make it a little difficult.

[dogren]

Stumped may be a little strong. After all, we are rookies. Can't talk to anybody who knows anything because they just tell you to bring it in ($150-$200 to "take a look"). The plugs/wires on top of the valve covers (outlined above) are what folks thought were the GP's. The relay clicks have folks scratching their heads a bit too. It's getting colder here in MN and the cold starts are getting worse. We're taking a closer look soon. Thanks again for the help. More later.... D.

[DmaxMaverick]

On top of the valve cover?? Are you refering to the GP relay, or 8 wires going into the valve covers? Those would be the injector harnesses. The GP relay is above the driver's side valve cover, at the rear.

The GP's are near the exhaust manifold. They will have a wire going to each of them, and the wire is connected by a nut, on a stud. The nut will be 7 or 8 mm.

If your starts are getting very labored when cold, you either have several plugs failed, or it is the relay. One or two failed GP's will barely be noticed. You really need to test those GP's. Remove the nut and wire, connect your ohm meter probes to the stud and a ground. An open circuit will be a failed plug.

[dogren]

Well, it's a done deal. Thanks again to DmaxMaverick. My model has one wire leading to a metal strip that attaches to all four GP's on each side. The strip is about 20 inches long and links all the GP's together. Removed the strips and all GP's checked good. Replaced the control box up-top. Cleared the code and waited 'till this morning. 22