1800: Throttle Position Switch (TPS)

[lotuseater]

Has my car (1800ES) got the original / correct Throttle Position Switch?
(D Jetronic fuel injection related topic)

I was about to order a replacement/ spare PCB from Ton Telgenhof in the Netherlands, but when I've checked the code on my TPS's PCB it is different to the ones he's showing on his list of images other than it appears similar to one from a BMW 3.0CSL

The PCB part number I have is: 1288 310 003

The TPS has 4 external contacts to the plug (no changes evident to wiring loom) and 3 soldered connections onto the PCB.

My engine runs 'OK' with this part as far as I can tell with it stationary - it's not back on the road yet, so not tested under load. Most things I read suggest that the TPS is not interchangeable with other models.

My 1800ES is early 1972, chassis: 1834352 - 000733 (UK RHD)

[Ron Kwas]

LE;

You show the early style TPS...see also: https://www.sw-em.com/bosch_d-jetron...TPS_Additional

Cheers

[142 Guy]

Your photograph is interesting. As Ron notes it is the early TPS that was applied to the 1970 and 1971 B20E equipped engines - in North America. The 1972 North American cars with the B20F got the later slanted comb style switch. However, my understanding is that non North American markets continued to receive the high compression B20E engine so perhaps those cars continued with the earlier design switch and controller?

Checking the part number on the D jet controller would indicate whether it was the earlier controller that matches up with the earlier switch. Aside from the slanted combs the primary difference in the later switch is the presence of the wide open throttle contact. However, my understanding is that the Volvo D jet systems did not use this function so the early switch may function correctly on a later system if the pin assignments are correct.

The photograph suggests that the TPS circuit board looks mostly OK. Unless the TPS fails its function check or there is damage present that is not obvious in the photograph I would not replace it. Carry out the contact function tests as described in the fault tracing manual

https://volvo1800pictures.com/docume...lt_tracing.pdf

If the TPS passes the function tests leave it alone. Keep the replacement circuit as a spare for future use. Degrease the contacts and wiper and apply some Deoxit D to the contacts and wiper surface to facilitate good operation. Make sure that the idle speed and the throttle switch adjustment are set up exactly as described in the fault tracing manual. Most TPS problems are related to incorrect adjustment.

An interesting animation of the operation of the early D jet TPS
https://volvo1800pictures.com/docume..._Operation.gif

The animation will show you how you can use a continuity tester connected to the various terminals of the TPS to check all the functions.

[Nullifie]

Be aware: using an early type TPS instead of the correct late type TPS (or late instead of early) needs swapping the thin white cables in the connector/plug that sticks in the TPS the other way around, the positions 1 2 3 4 count from the other side early <=> late.

[lotuseater]

Thank you all, for the knowledge and expertise.

You start to feel like you're getting to grips with the D Jet system (sense of achievement when you get the engine running after many years of sitting idle) and then you discover some anomaly over the TPS being correct or not.

I managed to refurb the dreaded AAV with a new waxstat bulb. Thermal timer is working (Phew!), cold start injector was brought back from the dead after several sessions in the ultrasonic tank, Injectors cleaned and service kit fitted, original fuel pump had corroded internally due to sitting idle - so sourced a recommended Porsche 924/944(?) item (proper Bosch unit that delivers a suitable 'low' pressure rather than the 60+ PSI that many more modern ones deliver. and under £100)
I also fitted a pre-filter before the pump to catch any tank debris.

My MAP sensor isn't holding the required pressure, so I'm deciding whether to send it to Bosch-Classic at £390 + shipping and probably import duties to UK from Germany or someone else who is skilled enough to repair - I contacted Dr D-Jet (also in Germany) who can repair them, but it sounds like he doesn't/isn't able to export out of the EU due to tax implications, as he only does it as a hobby, not as a business. It's a component that I don't have a 'spare', so need a trustworthy repairer.

Going back to the TPS:
I did set it up as per instructions using a 0.5mm feeler gauge under the throttle stop screw and getting it set just between those 2 fine switches at idle. The engine appears to respond OK - but I'm holding judgement until it's on the road. As you say, I'm intending to just clean it a little more and leave as it is for now. The new PCB is intended as a backup just in case - I think buying these parts whilst they are available makes sense, in case they stop making them in future.

My ECU appears to be date correct as per the list on Jetronic.org - Bosch number 0280000034 and it references the same MAP sensor that I have. Shame it doesn't specify the TPS for which I believe mine is part number 0280120012, which Ton (dutch guy that makes the PCB's) says was made by Bosch until May 1971.

(my car was first registered January 72 (so made in late 71 I guess)

I guess the important question is:

Is this TPS OK with that ECU ?

Is it possible Volvo used up stock of this type of TPS on early 1800ES production? My car is an original RHD that doesn't appear to have been mucked about with other than some of the body repairs (all now rectified).

Or has the TPS been retrofitted?
If we think the same TPS was fitted to US cars, then the same ECU is listed for US as for the non US cars from my understanding of the Jetronic.org info.

Hope you don't mind this lengthy post!

All feedback appreciated.

[Ron Kwas]

LE; Congrats on your progress!...lesser men would have given up long before this...!

Later TPS design is an improved mechanical design in terms of wear (Comb Contact edges at an angle to slider Direction of Travel, act as a soft ramp when Slider Contact comes along, decreasing wear, compared to "hard" edges 90 Deg [normal] to DoT), but that, and the inversion of contacts at external connector are the only difference! ...functionally, they are equivalent to your earlier style and can be interchanged. See: https://www.sw-em.com/D-Jet_Idle_Adj...inal_Locations

I strongly recommend periodic (GENTLE!) cleaning and lubing of TPS internals, especially the Comb Select and Idle Position Contacts (Drag Switches). See: https://www.sw-em.com/D-Jet_Idle_Adj...ed_Maintenance

Edit: Have you seen this info on MPS? http://www.sw-em.com/D-Jet_Manifold_Pressure_Sensor.htm ...includes source for a diaphragm repair kit (I have bought this kit from Tangerine Racing but not yet installed it...I'm working with Dave F. to develop an electronic tester with which to test and assure a successful rebuild and adjustment/calibration of a MPS).

142Guy; A couple of points..."the Volvo D jet systems did not use [WOT] function so the early switch may function correctly on a later system if the pin assignments are correct." Your understanding is correct...the WOT contact of the 5pin TPS used on other applications is not used in the Volvo application (5th pin WOT contact is ignored!), although 5Pin TPSs CAN be installed in a Volvo D-Jet application, if connected correctly. I have added some details to pics and drawings, earlier versions of which you may have already seen:



Cheers

[142 Guy]

Originally Posted by lotuseater

Going back to the TPS:
My ECU appears to be date correct as per the list on Jetronic.org - Bosch number 0280000034 and it references the same MAP sensor that I have. Shame it doesn't specify the TPS for which I believe mine is part number 0280120012, which Ton (dutch guy that makes the PCB's) says was made by Bosch until May 1971.

(my car was first registered January 72 (so made in late 71 I guess)

I guess the important question is:

Is this TPS OK with that ECU ?


Or has the TPS been retrofitted?
If we think the same TPS was fitted to US cars, then the same ECU is listed for US as for the non US cars from my understanding of the Jetronic.org info.

As Ron confirms, the early switch and the later switch function the same on the Volvo (which did not use the WOT contact). The prime difference is mechanical improvements. The terminal assignments are different; but, you can correct that by desoldering and repositioning the wires inside the switch (your switch shows no evidence of this) or depinning and repinning the wires on the 4 terminal plug that fits into the switch (easy to do and hard to detect).

With the hood open, engine off; but, the ignition in the run position manually operate the throttle shaft to open the throttle. As you go from full closed to full open you should hear the injectors clicking. I think it is 11 clicks; but, it has now been 10 years since I departed from D jet ownership so details are fuzzy. When you transition from open back to closed the clicks should be suppressed. If the switch passes this test then it is pretty much functionally correct. At that point whether or not it is the original switch is not important unless you are seeking concurs status.

My 1971 142E and my friends p1800E use the 0280 000 017 controller (Volvo part # 243182). According to my 140 parts manual the throttle switch associated with this controller is Volvo part # 461560 and is identical to your TPS. My car was built in June 1971 which looks to be close to the end of the 1971 production run.

My 140 parts manual covers up to the end of the 1972 model year and shows that for 1972 the 140 received the 0280 000 034 controller (Volvo part 243315). So this jives with your car. The parts manual shows that the 1972 cars continued to use the 461560 throttle switch. Based upon the 140 parts manual your throttle switch would be the correct switch for your 1972 model. If you can find an 1800 parts manual you could troll through the numbers to confirm that the 1800E / ES used the same TPS from 1970 to 1972.

Right now, I assign a high probability to your switch being the correct / original switch for your 1972.