major gauge issues

[whseguy]

i'm having major gauge issues like no tach no fuel no temp no speedo volt meter works though. i have an 85 shelby charger. also i ran the codes to see what the computer would tell me and it gave me a 13=map pneumatic circuit What does that mean? and a 34=? my book doesn't list this code what is 34?
on top of all that i don't hear my fuel pump kicking on should i hear it like most other mp-efi engines or not? or maybe a clogged fuel filter could be the culprit either way the car wont start. please help:confused2::banghead:

[whseguy]

is there any one online who can give me some pointers to these issues im kinda stuck.

[minigts]

Easiest thing to do is check the cable at the tranny and confirm your wires at junction points are good, like the bulk plug at the firewall and the 8 and 6 pin plugs from the lower harness. Then if you don't find anything wrong, see below.

If you have an 85 Charger and you don't have speedo, then you should pull your gauge cluster out and check everything. The speedo is manual, i.e., cable driven so it would either be disconnected there or at the tranny. But with the other ones, there are plug ins that go into the cluster, so pull the steering wheel and pull the cluster out to check it and make sure everything is plugged in securely in the back. You'll need to pull it anyways to hook the speedo back up.

And if you check codes, after the third key turn, it won't prime the pump or make the noise until after you get the car started again.

Not sure about 34, but I think it's a solenoid switch? Those throw codes, not critical to having the car start.

[minigts]

If you have ever pulled the gauge cluster out, it's possible you didn't hook them back up securely. They maybe came loose which is why things would be fine for a bit and then all of a sudden quit working.

[whseguy]

actually i just got a hold of this car and i'm trying to bring it back. the gauges never actually worked for me yet , so i have no clue if they are hooked up correctly or not , so if the tach is electrical also then there is a sensor at the other end of the wires from the cluster that would need checked right?

[minigts]

Well if all the gauges are not working, I would assume nothing was hooked up when the cluster was put back in the car. But the tach wire is white/blue going to the LM. It should hit the 40-way bulk and head across the firewall down to the pass. kick panel, I think. But get a puller, remove the steering wheel and check the cluster.

And the tach when plugged in but not working usually has a fault on the board on the back of the cluster. The solder points will come loose, so you just have to re-solder the ends.

[whseguy]

ok ill do that and see where it gets me thanks
:)

[whseguy]

ok, i got the coolant gauge to work and the oil pressure gauge, volt meter is fine and the speedo works. just the tach and fuel guages don't work, the wires in the cluster look ok . the person who owned the car before me has done something to the wiring harness. there were two wires spliced into the oil pressure wire, i hooked the right one to the sending unit and the gauge worked. the coolant gauge had a loose wire in the cluster. and i hooked the speedo in correctly this time and worked. now by all this elimination what could make the tach not work? the end to solder look ok i think. where does it read engine speed from?

[turzbo]

34 in my newer book is: open or shorted condition detected in the speed control vacume or vent solenoid circuits. book is for 87 to 94 not shur if it means much.

[whseguy]

ok, i got the coolant gauge to work and the oil pressure gauge, volt meter is fine and the speedo works. just the tach and fuel guages don't work, the wires in the cluster look ok . the person who owned the car before me has done something to the wiring harness. there were two wires spliced into the oil pressure wire, i hooked the right one to the sending unit and the gauge worked. the coolant gauge had a loose wire in the cluster. and i hooked the speedo in correctly this time and worked. now by all this elimination what could make the tach not work? the end to solder look ok i think. where does it read engine speed from?

any advice guys?:confused:

[minigts]

There should be a wire going to the LM, but I can't remember WHERE specifically it comes from or goes to. I will check my service manuals tonight and post the info. I'm running a SMEC now, so it comes from there in my car (I think), but I would imagine it is driven from the HEP. I'll have to look again, but I have the books for an 85.

[whseguy]

sorry but what is smec,and hep?
(i'm showing my ignorant side here...lol)

[minigts]

SMEC is the computer. Combined power module and logic board into one unit. The T1's and others up to like 87 or 88 had the logic module in the car and the power module in the engine bay. I don't know all the details, so my info is scattered and leaderless, similar to that of the "race of men".

The HEP is the Hall Effect Pickup. It goes under the cap and rotor on the distributor. There are wires leading from that to the LM and from there a wire for the tach. But again, I have the computer in my engine bay, so I cannot confirm these wires leave the HEP go to the computer and then go to the cluster. I'm going to get the manuals and see where everything runs and post in a bit.

[minigts]

Three wires from the Distributor Reference Pickup (black connector by the distributor, 3 wires) go to the logic module. There's an 18g Orange, 18 g Tan/Yellow and an 18g Gray/tracer. I would check continuity with these three and the tach wire (gray/ light blue).

The numbers corresponding to the wires starts 1 on the row of 13 OPPOSITE side of the notch of the RED connector.

The GY/LB (#12), OR (23) and GY* (#10) are all on the red connector of the LM. The Orange wire splices into a power wire from the power module and should read 7.5v.

The numbers corresponding to the wires starts 1 on the row of 13 of the SAME side of the notch of the BLUE connector.

The other wire TN/YL will be on the blue connector (#17).

[whseguy]

my hep has two sets of wires coming off it and they both have three wires. so go by color?
the red and blue connectors are the one on the lm right?
(afterthought.... i'm gonna need a mulitmeter aren't i?) :)

[minigts]

Well there are two, but the book only shows the black one. I believe the orange wire splices into gray one, too. Not sure the other color wires, but I think the gray 3 pin from the HEP has a purple/white (violet in the book :rolleyes:). And yes, invest in a $2 voltmeter, works wonders for solving problems.

Honestly, it really should be somewhere between the LM and the cluster. Your car would be having some issues if you weren't getting signal to the LM. In fact, I don't know if it would be running at all without that wire supplying voltage. A voltmeter should also read Ohms as well. You can easily test a wire for continuity by setting the meter to read Ohms and touching one end to the pin on the LM and the other to the wire where it hits the cluster. It should Ohm out to .01 or .001 or 1 depending on the meter setting. If it does, the wire is fine. If it doesn't and you have confirmed you are touching the same wire on both ends, then there is a break somewhere. That's how I test my stuff when looking for problems. Get the meter and do some testing. If you have questions, call me. 901.240.9059

[whseguy]

allrighty then a testing i will go. :)