| Author | Message | ||
| Bill Sebestyen (Bill308)
Junior Member Username: Bill308 Post Number: 131 Registered: 5-2001 |
Greg, If I recall correctly, you have a 78 308 GTS. The two cream colored boxes are indeed amplifiers and associated circuitry for the thermocouples fitted in your cats. The box with the pink wire going to it, if it is hooked up correctly, is a timer for the suction fan motor that removes fuel vapor from the air box and stores it in the carbon canistor. The remaining box is an electronic speed switch for control of the the electro valve. This electrovalve controls the air injection system. Incedently, there is no egr system on a 78 308 and this is probably true of all the carb 308's. | ||
| Ric Rainbolt (Ricrain)
New member Username: Ricrain Post Number: 38 Registered: 2-2002 |
I must disagree.  The two cream moudles are for the catalytic warning lights, yes. But, the silver one *IS* related to the EGR. For reference, if you wish, I can scan and post the schematic and/or owners manual pictures: The module is referred to as a "Electrovalve switch controlled by engine speed". In the schematic is referred to as "128 - Electronic speed switch for electrovalve 131" (131 is the EGR valve). | ||
| David Prall (Davidpra)
Junior Member Username: Davidpra Post Number: 81 Registered: 2-2001 |
PS, actually this system and its components are not related to the EGR systems. The EGR system's temp sensors are all in the engine compartment, and they are simple thermo-resistive switches which open or close in reponse to thermal loads. They supply current to the electrovlaves (3 on most 308's), which actuate to open and close vacuum passages connecting the EGR plumbing -- essentially, dumping exhaust gas back into the intake system, and mostly during idle (especially cold idle) operating conditions. | ||
| David Prall (Davidpra)
Junior Member Username: Davidpra Post Number: 80 Registered: 2-2001 |
Ric is correct: There are (2) Thermocouples in your cats (one in each) with leads that go to the cream colored modules -- which contain reference thermocouples potted in epoxy. The boxes (look to be Aluminum in your case, but are often plastic) contain a simple comparator logic circuit and a relay. The function of this system is to monitor catalytic converter temps and to send a warning (flashing 1/4 or 5/8 cylinder "slow down" lights on the dash) whenever the high temp limit is exceeded. I can't recall, so don't quote me on this, but I believe the limit temp is 1500F (may even be as high as 2000F). The purpose of this whole affair is that when your engine develops a misfire, unburnt fuel dumps into the exhaust system and becomes ignited in the catalytic converter (due to their high, normal operating temps). This will in turn elevate the cat temp beyond normal, and the system will flash its warning. This is very valuable because running the engine while exhausting unburnt fuel can damage cats as well as exhaust valves. I've also seen excessive cat temps weaken oil lines causing them to rupture --- very bad for the engine to catch fire and lose its oil supply! By the way, if you still have your owners manual for the car, it details this system both in functionality and with a complete wiring diagram. | ||
| Ric Rainbolt (Ricrain)
New member Username: Ricrain Post Number: 31 Registered: 2-2002 |
The two cream colored modules at the top are the thermocouple amplifiers that illuminate the "Slow Down X-Y" lights. One of the other modules controls EGR based on engine speed or somesuch thing. | ||
| Richelson (Richelson)
Member Username: Richelson Post Number: 659 Registered: 12-2001 |
I think that the one with the red mark is on the top side. I have the same boxes in my 308 and I think Greg just has the panel lying down. On mine the cream(with writing and wires) boxes are on the bottom and the others are on the top. I am not sure why it would click though. Sounds like a power issue. | ||
| Eric Eiland (Eric308gtsiqv)
Junior Member Username: Eric308gtsiqv Post Number: 229 Registered: 11-2001 |
Greg Rodgers, Was thumbing through an Electric Circuit Wiring Diagram Manual for the U.S. model year 84 - 85 308 QV's and stumbled accross the following diagram:  According to the manual, Fig. 4 - Controls & Displays, the items are listed as follows: Item No. 1 - Plate behind passenger's footrest. Item No. 129 - Timer for interior lights Item No. 121 - Unfastened safety belts device From the pic you posted, I was not positive as to the orientation of the panel relative to the circuit diagram -- in other words, which way was "up or down". It appears that the pic was taken viewing the panel from the top, so I would assume that the module in question (painted with red mark) is #121 - Unfastened safety belts device (?). This is just a shot in the dark here, so I'm not certain of any of this. Also, I'm not certain if this varies from year to year, Euro vs. US, etc. Just thought I'd pass the info. along in case it is of some help. | ||
| Greg Rodgers (Joechristmas)
Junior Member Username: Joechristmas Post Number: 171 Registered: 3-2001 |
If you remove the small piece of carpet in the passenger's side footwell. There is a metal piece with about 4-5 screws holding it in. Then it just slides out. Many put alarms in this compartment or subwoofers etc. I think one is a tach relay and emissions boxes?. | ||
| Greg Owens (Owens84qv)
Member Username: Owens84qv Post Number: 270 Registered: 10-2001 |
Greg, what did you remove or peel back to get to this unit? What is it? (You can tell I'm new with my 308!) | ||
| Greg Rodgers (Joechristmas)
Junior Member Username: Joechristmas Post Number: 169 Registered: 3-2001 |
I am wondering what is does this box on the left do? (with the red mark on it) Is it a tach relay? It was clicking around the 2000-3000rpm range. Any info would be great.  |